Online Etymology Dictionary

feller (n.): "one who fells (trees, etc.)," c. 1400, agent noun from fell (v.1). For the casual pronunciation of "fellow," see fella.
felloe (n.): "rim of a spoked wheel," early 15c., variant of felie (c. 1200), from Old English felga, plural of felg "rim of a wheel," from Proto-Germanic *felz- (source also of Old Saxon felga, Middle Dutch velge, Dutch velg, Old High German felga, German Felge).
fellow (n.): "companion, comrade," c. 1200, from Old English feolaga "partner, one who shares with another," from Old Norse felagi, from fe "money" (see fee) + lag, from a verbal base denoting "lay" (see lay (v.)). The root sense is of fellow is "one who puts down money with another in a joint venture."

Meaning "one of the same kind" is from early 13c.; that of "one of a pair" is from c. 1300. Used familiarly since mid-15c. for "any man, male person," but not etymologically masculine (it is used of women, for example, in Judges xi:37 in the King James version: "And she said unto her father, Let this thing be done for me: let me alone two months, that I may go up and down upon the mountains, and bewail my virginity, I and my fellows"). Its use can be contemptuous or dignified in English and American English, and at different times in its history, depending on who used it to whom, it has carried a tinge of condescension or insult. University senses (mid-15c., corresponding to Latin socius) evolved from notion of "one of the corporation who constitute a college" and who are paid from its revenues. Fellow well-met "boon companion" is from 1580s, hence hail-fellow-well-met as a figurative phrase for "on intimate terms."

In compounds, with a sense of "co-, joint-," from 16c., and by 19c. also denoting "association with another." Hence fellow-traveler, 1610s in a literal sense but in 20c. with a specific extended sense of "one who sympathizes with the Communist movement but is not a party member" (1936, translating Russian poputchik).

Fellow-countrymen formerly was one of the phrases the British held up to mock the Americans for their ignorance, as it is redundant to say both, until they discovered it dates from the 1580s and was used by Byron and others.
fellow-feeling (n.): 1610s, an attempt to translate the sense of Latin compassio and Greek sympatheia. See fellow (n.) + feeling (n.). It yielded a back-formed verb, fellow-feel in 17c., mercifully short-lived.
fellowship (n.): c. 1200, feolahschipe "companionship," from fellow + -ship. Sense of "a body of companions" is from late 13c. Meaning "spirit of comradeship, friendliness" is from late 14c. As a state of privilege in English colleges, from 1530s. In Middle English it was at times a euphemism for "sexual intercourse" (carnal fellowship).
To fellowship with is to hold communion with; to unite with in doctrine and discipline. This barbarism now appears with disgusting frequency in the reports of ecclesiastical conventions, and in the religious newspapers generally. [Bartlett, "Dictionary of Americanisms," 1848]
But Chaucer and Wyclif used it as a verb in Middle English, "to have fellowship with."
felo-de-se (n.): in old law use, "one who commits the felony of suicide," whether deliberately or in maliciously attempting to kill another, Latin, literally "one guilty concerning himself." See felon.
felon (n.): c. 1300, "one who deceives or commits treason; one who is wicked or evil; evil-doer," used of Lucifer and Herod, from Old French felon "evil-doer, scoundrel, traitor, rebel, oath-breaker, the Devil" (9c.), from Medieval Latin fellonem (nominative fello) "evil-doer," which is of uncertain origin, perhaps from Frankish *fillo, *filljo "person who whips or beats, scourger" (source of Old High German fillen "to whip"); or from Latin fel "gall, poison," on the notion of "one full of bitterness." Celtic origins also have been proposed.

Another theory (advanced by Professor R. Atkinson of Dublin) traces it to Latin fellare "to suck" (see fecund), which had an obscene secondary meaning in classical Latin (well-known to readers of Martial and Catullus), which would make a felon etymologically a "cock-sucker." OED inclines toward the "gall" explanation, but finds Atkinson's "most plausible" of the others.

Also by c. 1300 in English in a general legal sense "criminal; one who has committed a felony," however that was defined. Century Dictionary notes, "the term is not applicable after legal punishment has been completed." In Middle English it also was an adjective, "traitorous, wicked, malignant." Australian official James Mudie (1837), coined felonry "as the appellative of an order or class of persons in New South Wales,--an order which happily exists in no other country in the world."
felonious (adj.): mid-15c., "wicked, criminal" (implied in feloniously), from felony + -ous. Replaced felonous (mid-14c.) by c. 1600. Felonly (c. 1300) was another variation.
felony (n.): c. 1300, "treachery, betrayal; deceit; villainy, wickedness, sin, crime; violent temper, wrath; ruthlessness; evil intention," from Old French felonie (12c.) "wickedness, evil, treachery, perfidy, crime, cruelty, sin," from Gallo-Roman *fellonia, from fellonem "evil-doer" (see felon).

As a class of crime in common law, also from c. 1300, from Anglo-French. The exact definition changed over time and place, and even the distinction from misdemeanor or trespass is not always observed. In old use often a crime involving forfeiture of lands, goods, or a fee or a crime punishable by death. Variously used in the U.S.; often the sense is "crime punishable by death or imprisonment in a state penitentiary."
felsic (adj.): 1912, from feldspar + silica + -ic.
felt (n.): unwoven fabric matted together by rolling or beating while wet, Old English felt "felt," from West Germanic *feltaz "something beaten, compressed wool" (source also of Old Saxon filt, Middle Dutch vilt, Old High German filz, German Filz, Danish filt), from Proto-Germanic *felt- "to beat," from PIE *pel- (6) "to thrust, strike, drive" (source also of Old Church Slavonic plŭstĭ), with a sense of "beating" (see pulse (n.1)). Compare filter (n.). Felt-tipped pen (or -tip) is from 1953.
felt (v.1): "to make into felt," early 14c. (implied in felted); see felt (n.).
felt (v.2): past tense and past participle of feel (v.).
fem (n.): slang for "woman," by 1936, from female.
fem.: abbreviation of feminine (adj.).
female (n.): early 14c., from Old French femelle "woman, female" (12c.), from Medieval Latin femella "a female," from Latin femella "young female, girl," diminutive of femina "woman" (see feminine).
WHEN the Himalayan peasant meets the he-bear in his pride,
He shouts to scare the monster, who will often turn aside.
But the she-bear thus accosted rends the peasant tooth and nail.
For the female of the species is more deadly than the male.

[Kipling]
Sense extended in Vulgar Latin from young humans to female of other animals, then to females generally. Compare Latin masculus, also a diminutive (see masculine). Spelling altered late 14c. in erroneous imitation of male. In modern use usually as an adjective (early 14c.). Reference to implements with sockets and corresponding parts is from 1660s.
femaleness (n.): "quality of being female," 1886, from female + -ness. From 1892 as "qualities appropriate to a female."
femalist (n.): "a courter of women, a gallant," 1610s, from female + -ist.
feme covert (n.): "married woman" (legalese), c. 1600, French, from Old French feme coverte, second element fem. of covert "covered" (see covert). Contrasted to feme sole.
feminine (adj.): mid-14c., "of the female sex," from Old French femenin (12c.) "feminine, female; with feminine qualities, effeminate," from Latin femininus "feminine" (in the grammatical sense at first), from femina "woman, female," literally "she who suckles," from root of felare "to suck, suckle" (see fecund). Usual modern sense of "woman-like, proper to or characteristic of women" is recorded from mid-15c. Related: Femininely.

The interplay of meanings now represented roughly in female "characteristic of the sex that bears children," feminine "having qualities considered appropriate to a woman," and effeminate "having female qualities in a bad sense, unmanly," and the attempt to keep them clear of each other, has led to many coinages. Among nouns, in addition to feminity "womanishness," femininity, femaleness, feminineness (1810, "female qualities"), there is feminitude (1878); feminility "womanliness" (1824); feminie "womankind" (late 14c.); femality (17c., "effeminacy;" 1754 "female nature"); feminacy "female nature" (1829); feminicity "quality or condition of being a woman" (1843). Also feminality (1640s, "quality or state of being female"), from rare adjective feminal "female, belonging to a woman" (late 14c.), from Old French feminal. And femineity "quality or state of being feminine," also "effeminate; womanly," from Latin femineus "of a woman, pertaining to a woman." feminile "feminine" (1640s) seems not to have survived.
femininity (n.): late 14c., "feminine quality, womanliness, female nature," femynynytee, from feminine + -ity. From 1832 as "women collectively;" from 1853 as "character or state of being state of being a woman."
feminism (n.): 1851, "qualities of females;" 1895, "advocacy of women's rights;" from French féminisme (1837); see feminine + -ism. Also, in biology, "development of female secondary sexual characteristics in a male" (1875).
feminist (n.): 1892, from French féministe (1872); also see feminism. As an adjective by 1894. Womanist sometimes was tried as a native alternative. Femalist already had been taken as "courter of woman, a gallant" (1610s). Shaw coined hominist for "one who advocates for men the rights and privileges conventionally accorded to women."
feminity (n.): "quality or state of being feminine," late 14c., from Old French feminité, from Latin femina "woman, a female" (see feminine). From early 15c. as "women collectively."
feminization (n.): 1844, noun of action from feminize.
feminize (v.): 1650s, "make feminine or womanish," from Latin femina "woman, a female" (see feminine) + -ize. Related: Feminized; feminizing. Femalize (1670s, intransitive, 1709, transitive) and femininize (1868) are more rare.
femme (n.): French, literally "woman," from Old French feme, from Latin femina "woman, a female" (see feminine). Slang for "young woman" from 1928; meaning "passive and more feminine partner in a lesbian couple" attested by 1961.
femme fatale (n.): "attractive and dangerous woman," 1895, from French femme fatale, attested by 1844, from French femme "woman," from Latin femina (see feminine) + fatale (see fatal).
Une femme fatale est une femme qui porte malheur. [Jules Claretie, "La Vie a Paris," 1896]
Earlier, such a woman might be called a Circe.
femoral (adj.): 1782, from Medieval Latin femoralis, from stem of Latin femur "thigh" (see femur).
femur (n.): 1560s, at first in English as an architectural term; 1799 as "thighbone;" from Latin femur "thigh, upper part of the thigh," which is of unknown origin.
fen (n.): "low land covered wholly or partly by water," Old English fenn "mud, mire, dirt; fen, marsh, moor," from Proto-Germanic *fanjam- "swamp, marsh" (source also of Old Saxon feni, Old Frisian fenne, Middle Dutch venne, Dutch veen, Old High German fenna, German Fenn "marsh," Old Norse fen, Gothic fani "mud"), from PIE *pen- "swamp" (source also of Gaulish anam "water," Sanskrit pankah "bog, marsh, mud," Old Prussian pannean "swampland"). Italian and Spanish fango, Old French fanc, French fange "mud" are loan-words from Germanic. The native Latin word was limus or lutum.
fence (n.): early 14c., "action of defending, resistance; means of protection, fortification," shortening of defens (see defense). The same pattern also yielded fend, fender; and obsolete fensive "defensive" (late 16c.). Spelling alternated between -c- and -s- in Middle English. Sense of "enclosure" is first recorded mid-15c. on notion of "that which serves as a defense." Sense of "dealer in stolen goods" is thieves' slang, first attested c. 1700, from notion of such transactions taking place under defense of secrecy.

To be figuratively on the fence "uncommitted" is from 1828, perhaps from the notion of spectators at a fight, or a simple literal image: "A man sitting on the top of a fence, can jump down on either side with equal facility." [Bartlett, "Dictionary of Americanisms," 1848].
fence (v.): early 15c., "defend" (oneself); mid-15c. as "protect with a hedge or fence;" from fence (n.). From 1590s as "fight with swords," from the noun in this sense (1530s); see fencing. From 1610s as "knowingly buy or sell stolen goods." Related: Fenced.
fencer (n.): "swordsman," 1570s, agent noun from fence (v.)).
fencible (adj.): early 15c., "capable of making a defense," short for defensible; also see fence (n.). As a noun, "soldier enlisted to defend against invasion and not liable to serve abroad" (1796).
fencing (n.): mid-15c., "defending, act of protecting or keeping (something) in proper condition" (short for defencing); 1580s in the sense "art of using a sword or foil in attack and defense" (also fence-play); verbal noun from fence (v.). Meaning "putting up of fences" is from 1620s; that of "an enclosure" is from 1580s; meaning "receiving stolen goods" is from 1851 (see fence (n.)); meaning "materials for an enclosure" is from 1856.

Despite the re-enactment in 1285 of the Assize of Arms of 1181, fencing was regarded as unlawful in England. The keeping of fencing schools was forbidden in the City of London, "as fools who delight in mischief do learn to fence with buckler, and thereby are encouraged in their follies."
fend (v.): c. 1300, "defend, guard; protect; put up a fight; excuse or justify; forbid, bar," shortening of defend. From mid-14c. as "make a defense" and (usually with off (adv.)) "ward off, beat off, keep at a distance." Developed a meaning "make provision, give care" in Scottish English (16c.); hence to fend for oneself (1620s) "see to one's own defense." Related: Fended; fending.
fender (n.): late 13c., shortening of defender. Originally something hung over the side to protect the hull of a ship at a wharf, pier, etc. Of fireplaces since 1680s; of automobiles from 1919. Fender-bender "minor automobile accident" is from 1958.
fenestral (adj.): late 14c., "pertaining to windows," from Old French fenestral, from fenestre "window," from Latin fenestra (see fenestration).
fenestration (n.): 1870 in the anatomical sense, noun of action from Latin fenestrare, from fenestra "window, opening for light," a word perhaps from Etruscan. Meaning "arrangement of windows" as a design element in architecture is from 1846. Related: Fenestrated.
feng shui (n.): also feng-shui, fung-shui, 1797, from Chinese, from feng "wind" + shui "water." A system of spiritual influences in natural landscapes and a means of regulating them; "A kind of geomancy practiced by the Chinese for determining the luckiness or unluckiness of sites for graves, houses, cities, etc." [Century Dictionary].
Fenian (n.): 1816, a modern Irish blend of Old Irish feinne, plural of Fiann, name of a band of semi-legendary Irish warriors + Old Irish Fene, name of the ancient inhabitants of Ireland. In reference to Irish-American brotherhood of that name (founded 1857), attested by 1864.
fennec (n.): fox-like animal of Africa, 1790, from Arabic fenek, fanak "a name vaguely applied to various fur-bearing animals" [OED].
fennel (n.): Old English fenol, finul, finol "fennel," perhaps via (or influenced by) Old French fenoil (13c.) or directly from Vulgar Latin *fenuculum, from Latin feniculum/faeniculum, diminutive of fenum/faenum "hay," probably literally "produce" (see fecund). Apparently so called from its hay-like appearance and sweet odor.
fenugreek (n.): leguminous plant in western Asia and North Africa, Old English fenograecum, from Latin faenugraecum, literally "Greek hay," from faenum (see fennel) + Graecum (see Greek). The modern form in English is from Middle French fenugrec.
fer de lance (n.): large poisonous snake of American tropics, 1817, from French, "lance-head," literally "iron of a lance." So called for its shape.
feral (adj.): c. 1600, "wild, undomesticated," from Middle French feral "wild," from Latin fera, in phrase fera bestia "wild animal," from ferus "wild" (see fierce). Since 19c. commonly "run wild, having escaped from domestication."
Ferdinand: masc. proper name, Germanic, perhaps from Proto-Germanic *fardi-nanth- and meaning literally "adventurer," with first element perhaps Proto-Germanic *fardiz "journey," abstract noun related to or from *far- "to fare, travel" (see fare (v.)); second element is Proto-Germanic *nanthiz "risk," related to Old English neðan, Old High German nendan "to risk, venture."
fere (n.): "companion" (obsolete), from Middle English fere, a shortening of Old English gefera "associate, comrade, fellow-disciple; wife, man, servant," from Proto-Germanic *for-ja-, related to the root of faran "to go, travel" (see fare (v.)). Literally "one who goes with another." Compare German Gefährte "companion," from the same root; also, from causative *forjan-, Old High German fuoren. "to lead," modern German Fuhrer.
Fergus: masc. proper name, from Gaelic Fearghus or Old Irish Fergus "man-ability," first element cognate with Latin vir "man" (see virile); second from Old Irish gus "ability, excellence, strength, inclination," from Celtic root *gustu- "choice," from PIE root *geus- "to taste" (see gusto).