Online Etymology Dictionary

fawn (v.): Old English fægnian "rejoice, be glad, exult, applaud," from fægen "glad" (see fain); used in Middle English to refer to expressions of delight, especially a dog wagging its tail (early 13c.), hence "court favor, grovel, act slavishly" (early 14c.). Related: Fawned; fawning.
fawney (n.): "finger-ring," 1781, colloquial, from Irish fainne "ring."
fawning (adj.): mid-14c., present-participle adjective from fawn (v.). Related: Fawningly.
fax (n.): 1948, in reference to the technology, short for facsimile (telegraphy). Meaning "a facsimile transmission" is by 1980. The verb attested by 1970. Related: Faxed; faxing.
Futurists predict that a "fax" terminal in the house or business office may someday complement or even replace the mail-carrier. ["Scientific American," 1972]
fay (n.): "fairy," late 14c., from Old French fae (12c., Modern French fée), from Vulgar Latin *fata "goddess of fate," fem. singular of Latin fata (neuter plural), literally "the Fates" (see fate (n.)). Adjective meaning "homosexual" is attested from 1950s.
Fay: fem. proper name, in some cases from Middle English fei, Old French fei "faith," or else from fay "fairy."
faze (v.): 1830, American English, said to be a variant of Kentish dialect feeze "to frighten, alarm, discomfit" (mid-15c.), from Old English fesian, fysian "drive away, send forth, put to flight," from Proto-Germanic *fausjan (source also of Swedish fösa "drive away," Norwegian föysa). Related: Fazed; fazing. Bartlett (1848) has it as to be in a feeze "in a state of excitement." There also is a nautical verb feaze "to unravel" (a rope), from 1560s.
FBI: U.S. Federal Bureau of Investigation, formed 1935 from the former United States Bureau of Investigation (1908).
FCC: U.S. Federal Communications Commission, formed 1934 from the former Federal Radio Commission.
FDA: U.S. Food and Drug Administration, 1930, shortened from Food, Drug, and Insecticide Administration.
feal (adj.): "faithful," 1560s, not found in Middle English but apparently from Old French feal "faithful, loyal, true, sincere," collateral form of feeil, from Latin fidelis "loyal" (see fidelity).
feal (v.): "to hide, conceal," early 14c., a Northern English and Northern Midlands word, from Old Norse fela "to hide," from Proto-Germanic *felhan (source also of Gothic filhan "to hide, bury," Old English feolan "enter, penetrate, pass into").
fealty (n.): c. 1300, feaute, from Old French feauté, earlier fealte, "loyalty, fidelity; homage sworn by a vassal to his overlord; faithfulness," from Latin fidelitatem (nominative fidelitas) "faithfulness, fidelity," from fidelis "loyal, faithful" (see fidelity).
fear (n.): Middle English fere, from Old English fær "calamity, sudden danger, peril, sudden attack," from Proto-Germanic *feraz "danger" (source also of Old Saxon far "ambush," Old Norse far "harm, distress, deception," Dutch gevaar, German Gefahr "danger"), from PIE *pēr-, a lengthened form of the verbal root *per- (3) "to try, risk" (source also of Latin experiri "to try," periculum "trial, risk, danger;" Greek peria "trial, attempt, experience," empeiros "experienced;" Old Irish aire "vigilance;" Gothic ferja "watcher"). According to Watkins, this is "A verbal root belonging to the group of" *per- (1) "forward, through" (see per) via the notion of "to lead over, to press forward."

Sense of "state of being afraid, uneasiness caused by possible danger" developed by late 12c. Some Old English words for "fear" as we now use it were fyrhto, fyrhto; as a verb, ondrædan. Meaning "feeling of dread and reverence for God" is from c. 1400. To put the fear of God (into someone) "intimidate, cause to cower" is by 1888, from the common religious phrase; the extended use was often at first in colonial contexts:
Thus then we seek to put "the fear of God" into the natives at the point of the bayonet, and excuse ourselves for the bloody work on the plea of the benefits which we intend to confer afterwards. [Felix Adler, "The Religion of Duty," 1905]
fear (v.): Old English færan "to terrify, frighten," from a Proto-Germanic verbal form of the root of fear (n.). Cognates: Old Saxon faron "to lie in wait," Middle Dutch vaeren "to fear," Old High German faren "to plot against," Old Norse færa "to taunt."

Originally transitive in English; long obsolete in this sense but somewhat revived in digital gaming via "fear" spells, which matches the old sense "drive away by fear," attested early 15c. Meaning "feel fear" is late 14c. Related: Feared; fearing.
fearful (adj.): mid-14c., "causing fear," from fear (n.) + -ful. Meaning "full of fear, timid" (now less common) also is from mid-14c. As a mere emphatic, from 1630s. Related: Fearfully; fearfulness.
fearless (adj.): early 15c., from fear (n.) + -less. Related: Fearlessly; fearlessness.
fearsome (adj.): "causing fear," 1768, from fear (n.) + -some (1). Occasionally used badly in the sense "timid," which ought to stick to fearful. Related: Fearsomely; fearsomeness.
feasance (n.): "the performance of an obligation," 1530s, from Anglo-French fesance, from Old French faisance "action, deed, enactment," from faisant, present participle of faire "to make, do," from Latin facere (see factitious).
feasibility (n.): 1620s, from feasible + -ity.
feasible (adj.): "capable of being done, accomplished or carried out," mid-15c., from Anglo-French faisible, from Old French faisable "possible, that may be done; easy, convenient," from fais-, stem of faire "do, make," from Latin facere "to make, do, perform" (see factitious). Fowler recommends this word only for those "who feel that the use of an ordinary word for an ordinary notion does not do justice to their vocabulary or sufficiently exhibit their cultivation."
feasibly (adv.): 1640s, from feasible + -ly (2).
feast (n.): c. 1200, "secular celebration with feasting and entertainment" (often held on a church holiday); c. 1300, "religious anniversary characterized by rejoicing" (rather than fasting), from Old French feste "religious festival, holy day; holiday; market, fair; noise, racket; jest, fun" (12c., Modern French fête), from Vulgar Latin *festa (fem. singular; also source of Italian festa, Spanish fiesta), from Latin festa "holidays, feasts, festal banquets," noun use of neuter plural of festus "festive, joyful, merry," related to feriae "holiday" and fanum "temple," from Proto-Italic *fasno- "temple," from PIE *dhis-no- "divine, holy; consecrated place," from *dhes- "root of words in religious concepts" [Watkins].

The spelling -ea- was used in Middle English to represent the sound we mis-call "long e." Meaning "abundant meal" (whether public or private) is by late 14c. Meaning "any enjoyable occasion or event" is from late 14c.
feast (v.): c. 1300, "partake of a feast," from Old French fester "to feast, make merry; observe (a holiday)" (Modern French fêter), from feste "religious festival" (see feast (n.)). Related: Feasted; feasting.
feat (n.): mid-14c., "action, deeds," from Anglo-French fet, from Old French fait "action, deed, achievement" (12c.), from Latin factum "thing done," a noun based on the past participle of facere "make, do" (see factitious, and compare fact). Sense of "exceptional or noble deed" arose c. 1400 from phrase feat of arms (French fait d'armes).
feather (n.): Old English feðer "a feather; a pen," in plural, "wings," from Proto-Germanic *fethro (source also of Old Saxon fethara, Old Norse fioþr, Swedish fjäder, Middle Dutch vedere, Dutch veder, Old High German fedara, German Feder), from PIE *pet-ra-, from root *pet- "to rush, to fly" (see petition (n.)). Feather-headed "silly" is from 1640s. Feather-duster attested by 1835. Figurative use of feather in (one's) cap attested by 1734. Birds of a feather "creatures of the same kind" is from 1580s; the same image is in Greek homopteros.
feather (v.): Old English fiðerian "to furnish with feathers or wings," from feðer (see feather (n.)). Meaning "to fit (an arrow) with feathers" is from early 13c.; that of "to deck, adorn, or provide with plumage" is from late 15c. In reference to oars (later paddles, propellers, etc.) from 1740, perhaps from the notion of the blade turned edgewise, or from the spray of the water as it falls off (compare nautical feather-spray, that produced by the cutwater of a fast vessel). The noun in reference to this is from the verb. Meaning "cut down to a thin edge" is from 1782, originally in woodworking. Phrase feather one's nest "enrich oneself" is from 1580s. Related: Feathered; feathering.
feather-bed (n.): Old English feþerbedd; see feather (n.) + bed (n.).
feather-weight (n.): also featherweight, "lightest weight allowable by rules," 1812 (earlier as simply feather, 1760), from feather (n.) + weight (n.). Originally in horse-racing; boxing use as a specific weight class dates from 1889.
feature (n.): early 14c., "make, form, fashion" (obsolete), from Anglo-French feture, from Old French faiture "deed, action; fashion, shape, form; countenance," from Latin factura "a formation, a working," from past participle stem of facere "make, do, perform" (see factitious).

Sense of "facial characteristic" is mid-14c.; that of "any distinctive part" first recorded 1690s. Entertainment sense is from 1801; in journalism by 1855. Meaning "a feature film" is from 1913. Latin factura also is the source of Spanish hechura, Portuguese feitura, Italian fattura.
feature (v.): 1755, "to resemble, have features resembling," from feature (n.). The sense of "make special display or attraction of" is 1888; entertainment sense from 1897. Related: Featured; featuring.
featureless (adj.): 1816, from feature (n.) + -less.
features (n.): "parts of the visible body" (especially the face), c. 1300, from feature (n.).
featurette (n.): "short feature film," 1942, from feature (n.) in the cinematography sense + -ette.
febicches (pl.n.): also fibicches, fybicches, febicchis, febucches "contrivances, cheating tricks," late 14c., of unknown origin. Quirk suggests perhaps from Pebichios, name of an old alchemist.
febrifuge (n.): "medicine that reduces fever," 1680s, from French fébrifuge, literally "driving fever away," from Latin febris (see fever) + fugare "cause to flee, put to flight, drive off, chase away, rout," also used in reference to banishment and exile, derived verb from fuga "flight," from PIE *bhug-a-, suffixed form of root *bheug- (1) "to flee" (see fugitive (adj.)).
febrile (adj.): 1650s, from Medieval Latin febrilis "pertaining to fever," from Latin febris "a fever" (see fever).
February (n.): late 14c., ultimately from Latin februarius mensis "month of purification," from februare "to purify," from februa "purifications, expiatory rites" (plural of februum "means of purification, expiatory offerings"), which is of uncertain origin, said to be a Sabine word. De Vaan says from Proto-Italic *f(w)esro-, from a PIE word meaning "the smoking" or "the burning" (thus possibly connected with fume (n.)). The sense then could be either purification by smoke or a burnt offering.

The last month of the ancient (pre-450 B.C.E.) Roman calendar, so named in reference to the Roman feast of purification, held on the ides of the month. The Old English name for it was solmonað, which is said to mean "mud month." English first borrowed the Roman name from Old French Feverier, which yielded Middle English Feverer, Feoverel, etc. (c. 1200) before the 14c. respelling to conform to Latin.
fecal (adj.): 1540s; see feces + -al (1).
feces (n.): also faeces, c. 1400, "dregs," from Latin faeces "sediment, dregs," plural of faex (genitive faecis) "grounds, sediment, wine-lees, dregs," which is of unknown origin. Specific sense of "human excrement" is from 1630s in English but is not found in classical Latin. Hence Latin faex populi "the dregs of the people; the lowest class of society."
fecit: carved by workmen in old cathedrals, etc., "(he) made (it)," Latin third person singular perfect indicative of facere "to make" (see factitious).
feckless (adj.): 1590s, from feck, "effect, value, vigor" (late 15c.), Scottish shortened form of effect (n.), + -less. Popularized by Carlyle, who left its opposite, feckful, in dialectal obscurity. Related: Fecklessly; fecklessness.
feculent (adj.): "muddy, turbid, full of dregs or impurities," late 15c., from Middle French féculent, from Latin faeculentus "abounding in dregs," from stem faec- "sediment, dregs" (see feces) + adjective suffix -ulentus "full of." Related: Feculence.
fecund (adj.): a 16c. Latinizing revision of the spelling of Middle English fecond (early 15c.), from Middle French fecond (Old French fecont "fruitful"), from Latin fecundus "fruitful, fertile, productive; rich, abundant," from *fe-kwondo-, suffixed form (adjectival) of Latin root *fe-, corresponding to PIE *dhe(i)- "to suck, suckle," also "produce, yield."

Cognates include: Sanskrit dhayati "sucks," dhayah "nourishing;" Greek thele "mother's breast, nipple," thelys "female, fruitful;" Old Church Slavonic dojiti "to suckle," dojilica "nurse," deti "child;" Lithuanian dele "leech;" Old Prussian dadan "milk;" Gothic daddjan "to suckle;" Old Swedish dia "suckle;" Old High German tila "female breast;" Old Irish denaim "I suck," dinu "lamb."

Also from the same Latin root come felare "to suck;" femina "woman" (*fe-mna-, literally "she who suckles"); felix "happy, auspicious, fruitful;" fetus "offspring, pregnancy;" fenum "hay" (probably literally "produce"); and probably filia/filius "daughter/son," assimilated from *felios, originally "a suckling."
fecundity (n.): early 15c., from Latin fecunditatem (nominative fecunditas) "fruitfulness, fertility," from fecundus "fruitful, fertile" (see fecund).
fed (adj.): past participle adjective from feed (v.). Fed up "surfeited, disgusted, bored," is British slang first recorded 1900 (some early uses connect it to the Boer War), extended to U.S. by World War I; probably from earlier phrases like fed up to the back teeth. Earlier it was used of livestock, "fatten up by feeding." The notion probably is the same one in to have had enough "to have had too much."
fed (n.): 1788, short for Federalist; as colloquial for "official of the federal government," from 1916; especially, since 1930s, of FBI agents.
fedayeen (n.): partisans or irregulars in the Middle East, from Arabic plural of fedai "devotee, zealot, one who risks life for a cause," from Persian fidai.
federal (adj.): 1640s, as a theological term (in reference to "covenants" between God and man), from French fédéral, an adjective formed from Latin foedus (genitive foederis) "covenant, league, treaty, alliance," from PIE *bhoid-es-, from root *bheidh- "to trust" (which also is the source of Latin fides "faith;" see faith).

Secular meaning "pertaining to a covenant or treaty" (1650s) led to political sense of "formed by agreement among independent states" (1707), from use of the word in federal union "union based on a treaty" (popularized during formation of U.S.A. 1776-1787) and like phrases. Also from this period in U.S. history comes the sense "favoring the central government" (1788) and the especial use of the word (as opposed to confederate) to mean a state in which the federal authority is independent of the component parts within its legitimate sphere of action. Used from 1861 in reference to the Northern forces in the American Civil War.
federalism (n.): 1788, "doctrine of federal union in government," American English, from French fédéralisme, from fédéral (see federal). Also, from about the same time and place, "doctrines of the Federalist Party in American politics."