Online Etymology Dictionary

fatherhood (n.): early 14c., faderhade; see father (n.) + -hood.
fatherland (n.): "one's native country," 1620s, from father (n.) + land (n.). In modern use often a loan-translation of German Vaterland, itself a loan-translation of Latin patria (terra), literally "father's land." Similar formation in Dutch vaderland, Danish fædreland, Swedish fädernesland. Late Old English/Middle English fæderland (c. 1100) meant "parental land, inheritance."
fatherless (adj.): Old English fæderleas; see father (n.) + -less. Similar formation in Dutch vaderloos, German vaterlos, Danish faderlös.
fatherly (adj.): Old English fæderlic "fatherly, paternal; ancestral;" see father (n.) + -ly (1). Similar formation in Dutch vaderlijk, German väterlich. Related: Fatherliness.
fathom (n.): Old English fæðm "length of the outstretched arm" (a measure of about six feet), also "arms, grasp, embrace," and, figuratively "power," from Proto-Germanic *fathmaz "embrace" (source also of Old Norse faðmr "embrace, bosom," Old Saxon fathmos "the outstretched arms," Dutch vadem "a measure of six feet"), from PIE *pot(ə)-mo-, from root *petə- "to spread, stretch out" (see pace (n.)). It has apparent cognates in Old Frisian fethem, German faden "thread," which OED explains by reference to "spreading out." As a unit of measure, in an early gloss it appears for Latin passus, which was about 5 feet.
fathom (v.): Old English fæðmian "to embrace, surround, envelop," from a Proto-Germanic verb derived from the source of fathom (n.); cognates: Old High German fademon, Old Norse faþma. The meaning "take soundings" is from c. 1600; its figurative sense of "get to the bottom of, penetrate with the mind, understand" is from 1620s. Related: Fathomed; fathoming.
fathomable (adj.): 1630s, figurative; 1690s, literal; from fathom (v.) + -able.
fathomless (adj.): 1630s, literal ("bottomless"); 1640s, figurative ("not to be comprehended"); from fathom + -less.
fatigue (n.): 1660s, "that which causes weariness," from French fatigue "weariness," from fatiguer "to tire" (15c.), from Latin fatigare "to weary, to tire out," originally "to cause to break down," from pre-Latin adjective *fati-agos "driving to the point of breakdown," with first half from Old Latin *fatis, which is of unknown origin but apparently related to affatim (adv.) "sufficiently" and to fatisci "crack, split." The second half is the root of agere "to drive" (see act (n.)).

Especially "the labors of military persons" (1776). Meaning "a feeling of weariness from exertion" is from 1719. Of metals or other materials under strain, from 1877.
fatigue (v.): 1690s, from French fatiguer "to tire" (15c.), from fatigue (see fatigue (n.)). Earlier in same sense was fatigate (1530s), from Latin fatigatus, past participle of fatigare. Related: Fatigued; fatiguing; fatigation (c. 1500).
fatigues (n.): 1776, "extra duties of a soldier," from fatigue (n.). As a military clothing outfit, from 1836, short for fatigue dress (1833); fatigue cap is from 1824.
Fatimid: also Fatimite, in reference to the Arab dynasty that ruled 908-1171 in North Africa and sometimes Egypt and Syria, is from Fatima, daughter of Muhammad by his first wife, Khadija; Fatima married Ali, and from them the dynasty claimed descent.
fatling (n.): "lamb, kid, or other young animal fattened for slaughter," 1520s, from fat (n.) + -ling.
fatness (n.): Old English fætnesse; see fat (adj.) + -ness.
Fatso: nickname for a fat person, by 1944, elaboration of Fats, from fat (adj.).
fatten (v.): 1550s, "to make fat," from fat + -en (1). Intransitive sense from 1630s. Related: Fattened; fattener. The earlier verb was simply fat (v.).
fattening (adj.): "that makes fat," 1690s, present participle adjective from fatten. Earlier word was fatting (1530s).
fatty (adj.): late 14c., from fat + -y (2). As a name for a fat person, attested by 1797 (with -y (3)).
fatuity (n.): 1640s, from Middle French fatuité (14c.), from Latin fatuitatem (nominative fatuitas) "foolishness, folly," from fatuus "foolish, insipid" (see fatuous).
fatuous (adj.): "foolish, stupid," 1530s, from Latin fatuus "foolish, insipid, silly;" which is of uncertain origin. Buck suggests originally "stricken" in the head. But de Vaan says from Proto-Italic *fatowo- "of speech," from the PIE root of fame (n.).
[I]f we connect the fact that Fatuus is said to be an alternative name for Faunus, and that he predicted the future, and that this god is attested on an Etruscan mirror as Fatuvs in a clear oracular function (Weiss 2007b), we may venture a derivation from forfor 'to say' (Untermann 2000). The name of the god would then have come to be used pejoratively as 'silly'. [de Vaan]
Related: Fatuously; fatuousness.
fatwa (n.): 1620s, from Arabic fetwa "a decision given by a mufti," related to fata "to instruct by a legal decision." Popularized in English 1989 when Ayatollah Khomeini of Iran issued a ruling sentencing author Salman Rushdie to death for publishing "The Satanic Verses" (1988). This was lifted 1998.
faubourg (n.): "suburb," late 15c., from Middle French faux bourg, said by French authorities to be from Old French forsbourc (12c.) "suburbs, outskirts," literally "that which is outside the town," from fors "outside" (from Latin foris; see foreign) + bourc "town" (a word of Frankish origin cognate with English borough), and altered in Middle French by folk-etymology to faux bourg "false town" (suburbs were seen as inauthentic).
fauces (n.): "throat, gullet," 1540s, from Latin fauces "throat, gullet." Related: Faucal; faucial.
faucet (n.): c. 1400, from Old French fausset (14c.) "breach, spigot, stopper, peg (of a barrel)," which is of unknown origin; perhaps diminutive of Latin faux, fauces "upper part of the throat, pharynx, gullet." Not in Watkins, but Barnhart, Gamillscheg, and others suggest the Old French word is from fausser "to damage, break into," from Late Latin falsare (see false).

Spigot and faucet was the name of an old type of tap for a barrel or cask, consisting of a hollow, tapering tube, which was driven at the narrow end into a barrel, and a screw into the tube which regulated the flow of the liquid. Properly, it seems, the spigot was the tube, the faucet the screw, but the senses have merged or reversed over time. OED reports that faucet is now the common word in American English for the whole apparatus.
faugh (interj.): exclamation of disgust, by 1540s.
fault (n.): late 13c., faute, "deficiency," from Old French faute, earlier falte, "opening, gap; failure, flaw, blemish; lack, deficiency" (12c.), from Vulgar Latin *fallita "a shortcoming, falling," from Latin falsus "deceptive, feigned, spurious," past participle of fallere "deceive, disappoint" (see fail (v.)).

The -l- was restored 16c., probably in imitation of Latin, but the letter was silent until 18c. Sense of "physical defect" is from early 14c.; that of "moral culpability" (milder than sin or vice, but more serious than an error) is first recorded late 14c. Geological sense is from 1796. The use in tennis (c. 1600) is closer to the etymological sense.
fault (v.): "find fault with," mid-15c. from fault (n.). Earlier it was used in an intransitive sense of "be deficient" (late 14c., Scottish). Related: Faulted; faulter; faulting.
fault-finding (n.): 1620s, from verbal phrase find fault (with) (late 14c.); see fault (n.) + find (v.). Related: Fault-finder (1560s).
faultless (adj.): mid-14c., "having no blemishes or imperfections," from fault (n.) + -less. Meaning "having no blame, culpability, or guilt" is from 1570s. Related: Faultlessly; faultlessness.
faulty (adj.): "containing faults, errors, or defects," late 14c., from fault (n.) + -y (2). Related: Faultily; faultiness.
faun (n.): "rustic woodland spirit or demigod part human, part goat," late 14c., from Latin Faunus, the name of a god of the countryside, worshipped especially by farmers and shepherds, equivalent of Greek Pan. The faunalia were held in his honor. Formerly somewhat assimilated to satyrs, but they have diverged again lately.
The faun is now regarded rather as the type of unsophisticated & the satyr of unpurified man; the first is man still in intimate communion with Nature, the second is man still swayed by bestial passions. [Fowler]
The plural is fauni. The word is of uncertain origin. De Vaan suggests Proto-Italic *fawe/ono-, from a PIE word meaning "favorable," with cognates in Old Irish buan "good, favorable; firm," Middle Wensh bun "maiden, sweetheart."
fauna (n.): 1771, "the total of the animal life of a certain region or time, from Late Latin Fauna, a rustic Roman fertility goddess who was wife, sister, or daughter (or some combination) of Faunus (see faun).

Popularized by Linnaeus, who adopted it as a companion word to flora and used it in the title of his 1746 catalogue of the animals of Sweden, "Fauna Suecica." First used in English Gilbert White (1720-1793) the parson-naturalist.
faunal (adj.): "of or pertaining to a fauna," 1840, from fauna + -al (1).
Fauntleroy: in various usages, from the gentle boy hero of Frances Hodgson Burnett's popular novel "Little Lord Fauntleroy" (1885). The family name is recorded from mid-13c., literally "son of the king" (Anglo-French Le Enfant le Roy), from faunt, a Middle English variant of enfaunt (see infant). Middle English also had fauntekin "a little child" (late 14c.).
Faustian (adj.): 1870, in reference to Johann Faust (c. 1485-1541), German wandering astrologer and wizard, who was reputed to have sold his soul to the Devil. Fantastic tales of his life were told as early as the late 16c., and he was the hero of dramas by Marlowe and Goethe. The Latinized form of his name, faustus, means "of favorable omen."
Fauvist: movement in painting associated with Henri Matisse, 1915, from French fauve, "wild beast," a term applied in contempt to these painters by French art critic Louis Vauxcelles at Autumn Salon of 1905. The movement was a reaction against impressionism, featuring vivid use of colors. French fauve (12c.) in Old French meant "fawn-colored horse, dark-colored thing, dull," and is from Frankish *falw- or some other Germanic source, cognate with German falb "dun, pale yellowish-brown" and English fallow "brownish-yellow." Related: Fauvism (1912).
faux (adj.): from French faux "false" (12c., see false). Used with English words at least since 1676 (Etheredge, faux-prude). Used by itself, with French pronunciation, from 1980s to mean "fake."
faux pas (n.): "breech of good manners, any act that compromises one's reputation," 1670s, French, literally "false step." See false and pace (n.).
fave (n.): 1938, perhaps a "Variety" coinage, slang shortening of favorite (n.). Later also as an adjective.
Favonius: personification of the west wind in Roman mythology, from Latin Favonius, which de Vaan suggests is cognate with the god-name Faunus (see faun), from a prehistoric noun meaning "who favors" (see favor (n.)):
This also yields a good semantic motivation: the wind that stimulates vegetation can be called favourable. Favonius was regarded by the Romans as the herald of spring and the start of new vegetation (e.g. Cato Agr. 50.1, Cicero Ver. 5.27, Lucretius 1.11, Vitruvius 2.9.1).
The Latin word is the source (via Old High German phonno, 10c., via Vulgar Latin contraction *faonius) of German Föhn "warm, dry wind blowing down Alpine valleys." Related: Favonian.
favor (n.): c. 1300, "attractiveness, beauty, charm" (archaic), from Old French favor "a favor; approval, praise; applause; partiality" (13c., Modern French faveur), from Latin favorem (nominative favor) "good will, inclination, partiality, support," coined by Cicero from stem of favere "to show kindness to," from PIE *ghow-e- "to honor, revere, worship" (cognate: Old Norse ga "to heed").

Meaning "good will, kind regard" is from mid-14c. in English; sense of "act of kindness, a kindness done" is from late 14c. Meaning "bias, partiality" is from late 14c. Meaning "thing given as a mark of favor" is from late 15c. Phrase in favor of recorded from 1560s.
favor (v.): mid-14c., "to regard with favor, indulge, treat with partiality," from Old French favorer, from favor "a favor, partiality" (see favor (n.)). Meaning "to resemble, look somewhat like" is from c. 1600. Related: Favored; favoring.
favorable (adj.): late 14c., "kind, friendly," from Old French favorable "well-disposed, favorable, partial," from Latin favorabilis "favored, in favor," from favor "good will, partiality" (see favor (n.)). Meaning "advantageous" is from mid-15c. In Middle English it also meant "attractive, pleasing, agreeable." Related: Favorably.
favored (adj.): 1725, "enjoying unusual advantages," past-participle adjective from favor (v.). In compounds, "resembling, simulating," from c. 1400 (for example, well-favored "good-looking;" worst-favored "ugliest").
favorite (n.): "person or thing regarded with especial liking," 1580s, from Middle French favorit, perhaps via Italian favorito, noun use of past participle of favorire, from favore, from Latin favorem "inclination, partiality, support" (see favor (n.)).

Especially, "a person who gains dominant influence over a superior" (1590s). In racing, attested from 1813. As an adjective, by 1711. Favorite son in figurative use is from 1788. As a corresponding noun, "person who promotes the interests of another," Latin had fautor, hence Old French fauteur, Middle English fautour (early 14c.), but it has perished along with its fem. form fautress.
favoritism (n.): 1763, from favorite + -ism.
favour: chiefly British English spelling of favor (q.v.); for spelling, see -or. Related: Favourite; favouritism.
favourable (adj.): chiefly British English spelling of favorable; for spelling, see -or. Related: Favourably.
favous (adj.): "resembling a honeycomb," 1670s, from Latin favus "a honeycomb" + -ous.
fawn (n.): "young deer," mid-14c., from Anglo-French (late 13c.), Old French (12c.) faon, feon "young animal," especially "young deer," from Vulgar Latin *fetonem (nominative *feto), from Latin fetus "a bringing forth; an offspring" (see fetus). It was used of the young of any animal as recently as King James I's private translation of the Psalms, but the sense has been mainly of deer since 15c. Color use is by 1881.