Online Etymology Dictionary

tercel (n.): "male falcon," late 14c., from Old French tercel (c. 1200), from Medieval Latin tertiolus, from Latin tertius "third, a third," from root of tres "three" (see three). Various theories as to why it is called this; one says it's because the males are a third smaller than the females, another because a third egg in the nest (smaller than the other two) is believed always to produce a male bird.
owl (n.): Old English ule "owl," from Proto-Germanic *uwwalon- (source also of Middle Dutch, Dutch uil, Old High German uwila, German Eule, Old Norse ugla), a diminutive of PIE root *u(wa)l-, which is imitative of a wail or an owl's hoot (compare Latin ulula "owl;" also see ululation). The bird was employed proverbially and figuratively in reference to nocturnal habits, ugliness, and appearance of gravity and wisdom (often ironic).
titmouse (n.): small, active bird, early 14c., titmose, from tit (n.2), expressing something small, + Old English mase "titmouse," from Proto-Germanic *maison (source also of Dutch mees, German meise), from adj. *maisa- "little, tiny." Spelling influenced 16c. by unrelated mouse, "when mose had long been obsolete as an independent word" [OED]. The proper plural is titmouses.
peregrine (n.): also peregrin, type of falcon, 1550s, short for peregrine falcon (late 14c.), from Old French faulcon pelerin (mid-13c.), from Medieval Latin falco peregrinus, from Latin peregrinus "coming from foreign parts" (see peregrination). Sense may have been a bird "caught in transit," as opposed to one taken from the nest. Peregrine as an adjective in English meaning "not native, foreign" is attested from 1520s.
perk (v.): late 14c., "to make oneself trim or smart," perhaps from Old North French perquer "to perch" (Modern French percher; see perch (n.1)), on notion of a bird preening its plumage. Sense of "raise oneself briskly" is first attested 1520s; perk up "recover liveliness" is from 1650s. Related: Perked; perking.
hoot (v.): "to call or shout in disapproval or scorn," c. 1600, probably related to or a variant of Middle English houten, huten "to shout, call out" (c. 1200), which is more or less imitative of the sound of the thing. First used of bird cries, especially that of the owl, mid-15c. Meaning "to laugh" is from 1926. Related: Hooted; hooting. A hoot owl (1826) is distinguished from a screech owl.
pigeon (n.): late 14c. (early 13c. as a surname), from Old French pigeon "young dove" (13c.), probably from Vulgar Latin *pibionem, dissimilation from Late Latin pipionem (nominative pipio) "squab, young chirping bird" (3c.), from pipire "to peep, chirp," of imitative origin. Meaning "one easily duped" is from 1590s. Replaced culver (Old English culufre, from Vulgar Latin *columbra, from Latin columbula) and native dove.
bunting (n.2): lark-like bird, c. 1300, bountyng, of unknown origin. Perhaps from buntin "plump" (compare baby bunting, also Scots buntin "short and thick;" Welsh bontin "rump," and bontinog "big-assed"), or a double diminutive of French bon. Or it might be named in reference to speckled plumage and be from an unrecorded Old English word akin to German bunt "speckled," Dutch bont.
squab (n.): 1680s, "very young bird," earlier (1630s) "unformed, lumpish person" and used at various times for any sort of flabby mass, such as sofa cushions; probably from a Scandinavian word (compare dialectal Swedish skvabb "loose or fat flesh," skvabba "fat woman"), from Proto-Germanic *(s)kwab-. Klein lists cognates in Old Prussian gawabo "toad," Old Church Slavonic zaba "frog."
snipe (n.): long-billed marsh bird, early 14c., from Old Norse -snipa in myrisnipa "moor snipe;" perhaps a common Germanic term (compare Old Saxon sneppa, Middle Dutch snippe, Dutch snip, Old High German snepfa, German Schnepfe "snipe," Swedish snäppa "sandpiper"), perhaps originally "snipper." The Old English name was snite, which is of uncertain derivation. An opprobrious term (see guttersnipe) since c. 1600.
Sacagawea: also Sacajawea, name of the Shoshoni woman who accompanied the Lewis & Clark expedition.
She had been a captive among the Hidatsas (a Siouan people), and her Hidatsa name was tsaka'aka wi'a, lit. 'bird woman' (Hartley, 2002). Her Shoshoni name, rendered as Sacajawea and translated 'boat launcher,' may have been a folk-etymological transformation of the Hidatsa term (Shaul, 1972). [Bright]
Her image appeared on U.S. dollar coins from 2000.
gallinaceous (adj.): "of or resembling domestic fowl," 1783, from Latin gallinaceus "of hens, of fowls, pertaining to poultry," from gallina "hen," a fem. formation from gallus "cock," probably from PIE root *gal- (2) "to call, shout" (see call (v.)) as "the calling bird." But it also has an ancient association with Gaul (see Gallic), and some speculate that this is the source of the word, "on the assumption that the Romans became acquainted with the cock from Gaul, where it was brought by the Phoenicians" [Buck].
pounce (n.): "claw of a bird of prey," late 15c., pownse, probably from Old French ponchon "lance, javelin; spine, quill" (Modern French poinçon; see punch (v.)). So called for being the "claws that punch" holes in things. In falconry, the heel claw is a talon, and others are pounces. Meaning "an act of jumping or falling upon" is from 1825. In Middle English also the name of a tool for punching holes or embossing metal (late 14c.).
wagtail (n.): c. 1500, kind of small bird that has its tail in continuous motion (late 12c. as a surname), earlier wagstart (mid-15c.), from wag (v.) + tail (n.). From 18c. as "a harlot," but this sense seems to be implied much earlier:
If therefore thou make not thy mistress a goldfinch, thou mayst chance to find her a wagtaile. [Lyly, "Midas," 1592]
linnet (n.): small finch-like Eurasian songbird, 1530s, from Middle French linette "grain of flax," diminutive of lin "flax," from Latin linum "flax, linen thread" (see linen). Flaxseed forms much of the bird's diet. Old English name for the bird, linetwige, with second element perhaps meaning "to pluck," yielded Middle English and dialectal lintwhite. Also compare German Hänfling "linnet," from Hanf hemp.
magpie (n.): the common European bird, known for its chattering, c. 1600, earlier simply pie (early 13c.); first element from Mag, nickname for Margaret, long used in proverbial and slang English for qualities associated generally with women, especially in this case "idle chattering" (as in Magge tales "tall tales, nonsense," early 15c.; also compare French margot "magpie," from Margot, pet form of Marguerite).

Second element, pie, is the earlier name of the bird, from Old French pie, from Latin pica "magpie," fem. of picus "woodpecker," from PIE root *(s)peik- "woodpecker, magpie" (source also of Umbrian peica "magpie," Sanskrit pikah "Indian cuckoo," Old Norse spætr, German Specht "woodpecker"); possibly from PIE root *pi-, denoting pointedness, of the beak, perhaps, but the magpie also has a long, pointed tail. The birds are proverbial for pilfering and hoarding, can be taught to speak, and have been regarded since the Middle Ages as ill omens.
Whan pyes chatter vpon a house it is a sygne of ryghte euyll tydynges. [1507]
Divination by number of magpies is attested from c. 1780 in Lincolnshire; the rhyme varies from place to place, the only consistency being that one is bad, two are good.
genitive (adj.): late 14c., in reference to the grammatical case, from Old French genitif or directly from Latin (casus) genitivus "case expressing possession, source, or origin," from genitivus "of or belonging to birth," from genitus (past participle of gignere; see genital); misused by Latin grammarians to render Greek genike (ptosis) "the general or generic (case)," expressing race or kind, genikos also meaning "belonging to the family" (see genus). The noun meaning "the genitive case in grammar" is from 1610s.
The Latin genitivus is a mere blunder, for the Greek word genike could never mean genitivus. Genitivus, if it is meant to express the case of origin or birth, would in Greek have been called gennetike, not genike. Nor does the genitive express the relation of son to father. For though we may say, "the son of the father," we may likewise say, "the father of the son." Genike, in Greek, had a much wider, a much more philosophical meaning. It meant casus generalis, the general case, or rather the case which expresses the genus or kind. This is the real power of the genitive. If I say, "a bird of the water," "of the water" defines the genus to which a certain bird belongs; it refers to the genus of water-birds. [Max Müller, "Lectures on the Science of Language," 1861]
albatross (n.): 1670s, probably from Spanish or Portuguese alcatraz "pelican" (16c.), perhaps derived from Arabic al-ghattas "sea eagle" [Barnhart]; or from Portuguese alcatruz "the bucket of a water wheel" [OED], from Arabic al-qadus "machine for drawing water, jar" (from Greek kados "jar"), in reference to the pelican's pouch (compare Arabic saqqa "pelican," literally "water carrier"). Either way, the spelling was influenced by Latin albus "white." The name was extended, through some mistake, by English sailors to a larger sea-bird (order Tubinares).

Albatrosses were considered good luck by sailors; figurative sense of "burden" (1936) is from Coleridge's "Rime of the Ancient Mariner" (1798) about the bad luck of a sailor who shoots an albatross and then is forced to wear its corpse as an indication that he, not the whole ship, offended against the bird. The prison-island of Alcatraz in San Francisco Bay is named for pelicans that roosted there.
ostrich (n.): early 13c., from Old French ostruce "ostrich" (Modern French autruche) and Medieval Latin ostrica, ostrigius, all from Vulgar Latin avis struthio, from Latin avis "bird" (see aviary) + Late Latin struthio "ostrich," from Greek strouthion "ostrich," from strouthos megale "big sparrow," perhaps from PIE *trozdo- "thrush" (see thrush (n.1)). The Greeks also knew the bird as strouthokamelos "camel-sparrow," for its long neck. Among its proverbial peculiarities are indiscriminate voracity (especially a habit of swallowing iron and stone to aid digestion), want of regard for its eggs, and a tendency to hide its head in the sand when pursued.
Like the Austridge, who hiding her little head, supposeth her great body obscured. [1623, recorded in OED]
Ostriches do put their heads in the sand, but ostrich farmers say they do this in search of something to eat.
crane (n.): Old English cran "large wading bird," common Germanic (cognates: Old Saxon krano, Old High German krano, German Kranich, and, with unexplained change of consonant, Old Norse trani), from PIE *gere-no-, suffixed form of root *gere- (2) "to cry hoarsely," also the name of the crane (cognates: Greek geranos, Latin grus, Welsh garan, Lithuanian garnys "heron, stork"). Thus the name is perhaps an echo of its cry in ancient ears. Metaphoric use for "machine with a long arm" is first attested late 13c. (a sense also in equivalent words in German and Greek).
crow (n.): Old English crawe, imitative of bird's cry. Phrase eat crow is perhaps based on the notion that the bird is edible when boiled but hardly agreeable; first attested 1851, American English, but said to date to War of 1812 (Walter Etecroue turns up 1361 in the Calendar of Letter Books of the City of London). The image of a crow's foot for the wrinkles appearing with age at the corner of the eye is from late 14c. ("So longe mote ye lyve Til crowes feet be growen under youre ye." [Chaucer, Troilus and Criseyde, c. 1385]). Phrase as the crow flies recorded from 1800.
cuckold (n.): mid-13c., kukewald, from Old French cucuault, from cocu (see cuckoo) + pejorative suffix -ault, of Germanic origin. So called from the female bird's alleged habit of changing mates, or her authentic habit of leaving eggs in another bird's nest.

In Modern French the identity is more obvious: Coucou for the bird and cocu for the betrayed husband. German Hahnrei (13c.), from Low German, is of obscure origin. The second element seems to be connected to words for "ardent," and suggests perhaps "sexually aggressive hen," with transferal to humans, but Kluge suggests rather a connection to words for "capon" and "castrated." Related: Cuckoldry.
hackle (n.): Old English hacele "coat, cloak, vestment, mantle" (cognate with Old High German hachul, Gothic hakuls "cloak;" Old Norse hekla "hooded frock"), of uncertain origin. The same word with a sense of "bird plumage" is first recorded early 15c., though this might be from unrelated Middle English hackle "flax comb" (see heckle (n.)) on supposed resemblance of comb to ruffled feathers, or from an unrecorded continental Germanic word. Metaphoric extension found in phrases such as raise (one's) hackles (as a cock does when angry) is by 1881.
jinx (n.): 1911, American English, originally baseball slang; perhaps ultimately from jyng "a charm, a spell" (17c.), originally "wryneck" (also jynx), a bird used in witchcraft and divination, from Latin iynx "wryneck," from Greek iynx. Jynx was used in English as "a charm or spell" from 1690s.
Most mysterious of all in the psychics of baseball is the "jinx," that peculiar "hoodoo" which affects, at times, a man, at other times a whole team. Let a man begin to think that there is a "jinx" about, and he is done for for the time being. ["Technical World Magazine," 1911]
The verb is 1912 in American English, from the noun. Related: Jinxed; jinxing.
kibitz (v.): "a looker-on," 1920, from kibitz (v.), American English, 1915, from Yiddish kibitsen "to offer gratuitous advice as an outsider," from German kiebitzen "to look on at cards, to kibitz," originally in Rotwelsch (thieves' cant) "to visit," from Kiebitz, name of a shore bird (European pewit, lapwing) with a folk reputation as a meddler, from Middle High German gibitz "pewit," imitative of its cry. Young lapwings are proverbially precocious and active, and were said to run around with half-shells still on their heads soon after hatching. Related: Kibitzing. Also see kibitzer.
eagle (n.): mid-14c., from Old French egle, from Old Provençal aigla, from Latin aquila "black eagle," fem. of aquilus, often explained as "dark colored" (bird); see aquiline. The native term was erne. Golf score sense is by 1908 (according to old golf sources, because it "soars higher" than a birdie). As the name of a U.S. $10 coin minted from 1792 to 1933, established in the 1786 resolution for a new monetary system (but at first only the desperately needed small copper coins were minted). The figurative eagle-eyed is attested from c. 1600.
Jenny: fem. personal name, originally another form of Jane, Janey and a diminutive of Jane or Janet; in modern use (mid-20c.) typically a shortening of Jennifer. Jenny is attested from c. 1600 as female equivalent of jack (n.), and like it applied to animals (especially of birds, of a heron, a jay, but especially Jenny wren, 1640s, in bird-fables the consort of Robin Redbreast). Also like jack used of machinery; Akrwright's spinning jenny (1783) is said to have been named for his wife, but is perhaps rather a corruption of gin (n.2) "engine."
quarry (n.1): "what is hunted," early 14c., quirre "entrails of deer placed on the hide and given to dogs of the chase as a reward," from Anglo-French quirreie, Old French cuiriee "the spoil, quarry" (Modern French curée), altered (by influence of Old French cuir "skin," from Latin corium "hide"), from Old French corée "viscera, entrails," from Vulgar Latin *corata "entrails," from Latin cor "heart," from PIE root *kerd- (1) "heart" (see heart (n.)). Sense of "anything chased in hunt" is first recorded 1610s; earlier "bird targeted by a hawk or other raptor" (late 15c.).
quail (n.): migratory game bird, late 14c. (early 14c. as a surname (Quayle), from Old French quaille (Modern French caille), perhaps via Medieval Latin quaccula (source also of Provençal calha, Italian quaglia, Old Spanish coalla), or directly from a Germanic source (compare Dutch kwakkel, Old High German quahtala "quail," German Wachtel, Old English wihtel), imitative of the bird's cry. Or the English word might be directly from Proto-Germanic. Slang meaning "young attractive woman" first recorded 1859.
e-mail: 1982, short for electronic mail (1977; see electronic + mail (n.1)); this led to the contemptuous application of snail mail (1983) to the old system.
Even aerial navigation in 1999 was found too slow to convey and deliver the mails. The pneumatic tube system was even swifter, and with such facilities at hand it is not surprising that people in San Francisco received four daily editions of the Manhattan journals, although the distance between Sandy Hook and the Golden Gate is a matter of 3,600 miles. ["Looking Forward," Arthur Bird, 1899]
Associated Press style guide collapsed it to email 2011.
chant (v.): late 14c., from Old French chanter "to sing, celebrate" (12c.), from Latin cantare "to sing," originally frequentative of canere "sing" (which it replaced), from PIE root *kan- "to sing" (source also of Greek eikanos "cock," Old English hana "cock," both literally "bird who sings for sunrise;" Old Irish caniaid "sings," Welsh canu "sing"). The frequentative quality of the word was no longer felt in Latin, and by the time French emerged the word had entirely displaced canere. Related: Chanted; chanting.
gnat (n.): Old English gnæt "gnat, midge, small flying insect," earlier gneat, from Proto-Germanic *gnattaz (source also of Low German gnatte, German Gnitze); perhaps literally "biting insect" and related to gnaw.
The gnatte is a litil fflye, and hatte culex he soukeþ blood and haþ in his mouþ a pipe, as hit were a pricke. And is a-countid a-mong volatiles and greueþ slepinge men wiþ noyse & wiþ bytinge and wakeþ hem of here reste. [John of Trevisa, translation of Bartholomew de Glanville's "De proprietatibus rerum," 1398]
Gnat-catcher, insectivorous bird of the U.S. woodlands, is from 1823.
heron (n.): "long-necked, long-legged wading bird," c. 1300, from Old French hairon, eron (12c.), earlier hairo (11c., Modern French héron), from Frankish *haigiro or some other Germanic source, from Proto-Germanic *hraigran. Related to Old High German heigaro, Danish hejre "heron," German Reiher, Dutch reiger, Old Norse hegri), perhaps from a common IE root imitative of its cry (compare Old Church Slavonic kriku "cry, scream," Lithuanian kryksti "to shriek," Welsh cregyra "heron," Latin graculus "jackdaw, crow"). Old English cognate hraga did not survive into Middle English. Egret is from the same source.
pelican (n.): Old English pellicane, from Late Latin pelecanus, from Greek pelekan "pelican" (so used by Aristotle), apparently related to pelekas "woodpecker" and pelekys "ax," perhaps so called from the shape of the bird's bill. Spelling influenced in Middle English by Old French pelican. Used in Septuagint to translate Hebrew qaath. The fancy that it feeds its young on its own blood is an Egyptian tradition properly belonging to some other bird. Louisiana has been known as the Pelican state at least since 1859.
loony (adj.): also loonie, looney, 1853, American English, short for lunatic, but also influenced by loon (n.2) and perhaps loon (n.1), the bird being noted for its wild cry and method of escaping from danger. As a noun by 1884, from the adjective. Slang loony bin "insane asylum" is from 1919. Looney left in reference to holders of political views felt to be left-wing in the extreme is from 1977. Looney Tunes, Warner Bros. studios' animated cartoon series, dates from 1930.
tit (n.2): 1540s, a word used for any small animal or object (as in compound forms such as titmouse, tomtit, etc.); also used of small horses. Similar words in related senses are found in Scandinavian (Icelandic tittr, Norwegian tita "a little bird"), but the connection and origin are obscure; perhaps, as OED suggests, the word is merely suggestive of something small. Used figuratively of persons after 1734, but earlier for "a girl or young woman" (1590s), often in deprecatory sense of "a hussy, minx."
penguin (n.): 1570s, originally used of the great auk of Newfoundland (now extinct), shift in meaning to the Antarctic bird (which looks something like it, found by Drake in Magellan's Straits in 1578) is from 1580s. Of unknown origin, though often asserted to be from Welsh pen "head" (see pen-) + gwyn "white" (see Gwendolyn), but Barnhart says the proposed formation is not proper Welsh. The great auk had a large white patch between its bill and eye. The French and Breton versions of the word ultimately are from English.
petrel (n.): seabird, 1670s, pitteral, modern spelling first recorded 1703 by English explorer William Dampier (1651-1715), who wrote the bird was so called from its way of flying with its feet just skimming the surface of the water, which recalls the apostle's walk on the sea of Galilee (Matt. xiv:28); if so, it likely was formed in English as a diminutive of Peter (Late Latin Petrus). If this is folk etymology, the true source of the name is undiscovered. French pétrel (1760) probably is from English.
clip (v.1): "to cut or sever with a sharp instrument," c. 1200, from a Scandinavian source (compare Old Norse klippa, Swedish klippa, Danish klippe "clip, shear, cut"), which is probably echoic. Related: Clipped; clipping.

Meaning "to pronounce short" is from 1520s. The verb has a long association with shady activities, originally especially in reference to cutting or shaving metal from coins (c. 1400), but later extended to swindles from the sense "to shear sheep," hence clip-joint "place that overcharges outrageously" (1933, American English, a term from Prohibition). To clip (someone's) wings figuratively (1590s) is from the method of preventing a captive bird from flying.
pheasant (n.): late 13c. (mid-12c. as a surname), from Anglo-French fesaunt, Old French faisan (13c.) "pheasant," from Latin phasianus, from Greek phasianos "a pheasant," literally "Phasian bird," from Phasis, river flowing into the Black Sea in Colchis, where the birds were said to have been numerous. The ph- was restored in English late 14c. (see ph). The excrescent -t is due to confusion with -ant suffix of nouns formed from present participle of verbs in first Latin conjugation (peasant, tyrant, etc.).
skyscraper (n.): very tall urban building, 1888, in a Chicago context, from sky (n.) + agent noun of scrape (v.). Used earlier for "ornament atop a building" (1883), "very tall man" (1857), "high-flying bird" (1840), "light sail at the top of a mast" (1794), and the name of a racehorse (1789). Compare cognate French gratte-ciel, from gratter "to scrape" + ciel "sky;" German Wolkenkratzer, from Wolke "cloud" + Kratzer "scraper."
cloud-cleaver, an imaginary sail jokingly assumed to be carried by Yankee ships. [W. Clark Russell, "Sailors' Word Book," 1883]
stilt (n.): early 14c., "a crutch," a common Germanic word (cognates: Danish stylte, Swedish stylta, Middle Low German, Middle Dutch stelte "stilt," Old High German stelza "plow handle, crutch"), though the exact relationship of them all is unclear, from Proto-Germanic *steltijon, from PIE root *stel- "to put, stand" (see stall (n.1)). Application to "wooden poles for walking across marshy ground, etc." is from mid-15c. Meaning "one of the posts on which a building is raised from the ground" is first attested 1690s. As a type of bird with long legs, from 1831. Stilted in the figurative sense of "pompous, stuffy" is first recorded 1820.
swallow (n.1): type of migratory bird (family Hirundinidae), Old English swealwe "swallow," from Proto-Germanic *swalwon (source also of Old Saxon, Old Norse, Old Frisian, Swedish svala, Danish svale, Middle Dutch zwalewe, Dutch zwaluw, Old High German swalawa, German Schwalbe), from PIE *swol-wi- (source also of Russian solowej, Slovak slavik, Polish słowik "nightingale"). The etymological sense is disputed. Popularly regarded as harbingers of summer; swallows building nests on or near a house is considered good luck.
hen (n.): Old English henn "hen," from West Germanic *hannjo (source also of Old Frisian henn, Middle Dutch henne, Old High German henna), fem. of *han(e)ni "male fowl, cock" (source of Old English hana "cock"), literally "bird who sings (for sunrise)," from PIE root *kan- "to sing" (see chant).

The original masculine word survives in German (Hahn "cock"), Swedish, Danish, etc. German also has a generic form, Huhn, for either gender of the bird. Extension to "female of any bird species" is early 14c. in English. Hen as slang for "woman" dates from 1620s; hence hen party "gathering of women," first recorded 1887. To be mad as a wet hen is from 1823, but the figure was used to indicate other states:
Some, on the contrary, are viciously opposite to these, who act so tamely and so coldly, that when they ought to be angry, to thunder and lighten, as one may say, they are no fuller of Heat, than a wet Hen, as the Saying is; .... ["Life of Mr. Thomas Betterton," London, 1710]

Orth. Out upon you for a dastardly Fellow; you han't the Courage of a wet Hen. ["A Sermon Preached at St. Mary-le-Bow, March 27, 1704"]
As wanton as a wet hen is in "Scots Proverbs" (1813). Among Middle English proverbial expressions was nice as a nonne hen "over-refined, fastidiously wanton" (c. 1500); to singen so hen in snowe "sing miserably," literally "sing like a hen in snow" (c. 1200). The figure of the hen with one chick dates to 1590s. Hen's teeth as a figure of scarceness is attested by 1838.
jay (n.): the common European jay (Garrulus glandarinus), early 14c. (late 12c. as a surname), from Old North French gai, Old French jai "magpie, jay" (12c., Modern French geai), from Late Latin gaius "a jay," probably echoic of the bird's harsh warning cry and supposedly influenced by Latin Gaius, a common Roman proper name.

For other bird names from proper names, compare martin and parrot. Applied to the North American blue jay (Cyanocitta cristata) from 1709; it is unrelated but has similar vivid markings, is noisy and restless, and also has a harsh call. Applied to humans in sense of "impertinent chatterer, loud, flashy dresser" from 1520s. Jolly as a jay was a Middle English expression for "very happy, joyful."
hat (n.): Old English hæt "hat, head covering" (variously glossing Latin pileus, galerus, mitra, tiara), from Proto-Germanic *hattuz "hood, cowl" (source also of Frisian hat, Old Norse hattr, höttr "a hood or cowl"), from PIE root *kadh- "cover, protect" (source also of Lithuanian kudas "tuft or crest of a bird," Latin cassis "helmet"). To throw one's hat in the ring was originally (1847) to take up a challenge in prize-fighting. To eat one's hat (1770), expressing what one will do if something he considers a sure thing turns out not to be, is said to have been originally eat Old Rowley's [Charles II's] hat.
fern (n.): Old English fearn "fern," from Proto-Germanic *farno- (source also of Old Saxon farn, Middle Dutch vaern, Dutch varen, Old High German farn, German Farn). Watkins and other sources propose an etymology on the notion of "having feathery fronds" from a possible PIE *por-no- "feather, wing" (source also of Sanskrit parnam "feather;" Lithuanian papartis "fern;" Russian paporot'; Greek pteris "fern"), a proposed suffixed form of the root *per- (2) "to lead, pass over" on the notion of "that which carries a bird in flight" (see port (n.1)).

The plant's ability to appear as if from nothing accounts for the ancient belief that fern seeds conferred invisibility (1590s). Filicology "science or study of ferns" (1848) is from Latin filix "fern."
nest (n.): Old English nest "bird's nest, snug retreat," also "young bird, brood," from Proto-Germanic *nistaz (source also of Middle Low German, Middle Dutch nest, German Nest), from PIE *nizdo- (source also of Sanskrit nidah "resting place, nest," Latin nidus "nest," Old Church Slavonic gnezdo, Old Irish net, Welsh nyth, Breton nez "nest"), probably from *ni "down" + *sed- (1) "to sit" (see sedentary).

Used since Middle English in reference to various accumulations of things (such as a nest of drawers, early 18c.). Nest egg "retirement savings" is from 1700, originally "a real or artificial egg left in a nest to induce the hen to go on laying there" (c. 1600).
aisle (n.): late 14c., ele, "lateral division of a church (usually separated by a row of pillars), from Old French ele "wing (of a bird or an army), side of a ship" (12c., Modern French aile), from Latin ala, related to axilla "wing, upper arm, armpit; wing of an army," from PIE *aks- "axis" (see axis), via a suffixed form *aks-la-. The root meaning in "turning" connects it with axle and axis.

Confused from 15c. with unrelated ile "island" (perhaps from notion of a "detached" part of a church), and so it took an -s- when isle did, c. 1700; by 1750 it had acquired an a-, on the model of French cognate aile. The word also was confused with alley, which gave it the sense of "passage between rows of pews or seats" (1731), which was thence extended to railway cars, theaters, etc.
flamen (n.): "ancient Roman priest," 1530s, from Latin flamen "a priest of one deity," which is of unknown origin, perhaps from PIE root *bhlad- "to worship" (source also of Gothic blotan, Old English blotan "to sacrifice"). Also used from early 14c., in imitation of Geoffrey of Monmouth, in reference to ancient pre-Christian British priests. Related: Flamineous.
The old connection of flamen with Skt. brahman- is highly problematic, and has been dismissed by Schrijver. As WH surmise, the ending -en points to an archaism, probably a n[euter] noun "sacrificial act" which changed its semantics to 'priest'; for a similar shift, cf. augur "bird-observer" .... The only viable comparanda are found in [Germanic], but they show root-final (or suffixal) *-d~. [de Vaan]