Online Etymology Dictionary

feebleminded (adj.): 1530s; see feeble + mind. Related: Feeblemindedness.
feebleness (n.): c.1300, from feeble + -ness.
feebly (adv.): late 13c., from feeble + -ly (2).
feed (v.): Old English fedan "nourish, feed, sustain, foster," from Proto-Germanic *fodjan (cf. Old Saxon fodjan, Old Frisian feda, Dutch voeden, Old High German fuotan, Old Norse foeða, Gothic fodjan "to feed"), from PIE *pa- "to protect, feed" (see food). Feeding frenzy is from 1989, metaphoric extension of a phrase that had been used of sharks since 1950s.
feed (n.): "action of feeding," 1570s, from feed (v.). Meaning "food for animals" is first attested 1580s. Of machinery, from 1892.
feedback (n.): 1920, in the electronics sense, from feed + back (adj.). Transferred use, "information about the results of a process" is attested by 1955.
feeder (n.): early 15c., "one who feeds an animal;" 1560s, "one who eats;" agent noun from feed. As a mechanical apparatus, from 1660s. Of cattle and streams, by 1790s; of roads and railroads, by 1850s.
feel (v.): Old English felan "to touch, perceive," from Proto-Germanic *foljan (cf. Old Saxon gifolian, Old Frisian fela, Dutch voelen, Old High German vuolen, German fühlen "to feel," Old Norse falma "to grope"), from PIE root *pal- "to touch, feel, shake, strike softly" (cf. Greek psallein "to pluck (the harp)," Latin palpare "to touch softly, stroke," palpitare "to move quickly"), perhaps ultimately imitative.

The sense in Old English was "to perceive through senses which are not referred to any special organ." Sense of "be conscious of a sensation or emotion" developed by late 13c.; that of "to have sympathy or compassion" is from c.1600. To feel like "want to" attested from 1829.
feel (n.): early 13c., "sensation, understanding," from feel (v.). Meaning "action of feeling" is from mid-15c. "Sensation produced by something" is from 1739. Noun sense of "sexual grope" is from 1932; from verbal phrase to feel (someone) up (1930).
feeler (n.): early 15c., "one who feels," agent noun from feel (v.). Of animal organs, 1660s. Transferred sense of "proposal put forth to observe the reaction it gets" is from 1830. Related: Feelers.
feeling (n.): late 12c., "act of touching, sense of touch," verbal noun from feel (v.). Meaning "emotion" is mid-14c. Meaning "what one feels (about something), opinion" is from mid-15c. Meaning "capacity to feel" is from 1580s. Related: Feelingly.
feelings (n.): "tender or sensitive side of one's nature," 1771, from plural of feeling.
feet (n.): plural of foot (n.).
feign (v.): c.1300, from Old French feign-, present participle stem of feindre "pretend, represent, imitate, shirk" (12c.), from Latin fingere "to touch, handle; devise; fabricate, alter, change" (see fiction). Related: Feigned; feigning.
feint (n.): 1670s, "a false show, a pretended blow," from French feinte "a feint, sham," abstract noun from Old French feint (13c.) "false, deceitful," originally fem. past participle of feindre (see feign).

Borrowed late 13c. as adjective, but now obsolete in that sense. Also as a noun in Middle English with sense "false-heartedness" (early 14c.), also "bodily weakness" (c.1400).
feint (v.): c.1300, feinten, "to deceive, pretend," also "become feeble or exhausted; to lack spirit or courage," from feint (adj.); see feint (n.). Cf. Old French feintir "be slow, delay." Sense of "to make a sham attack" is first attested 1833. Related: Feinted; feinting.
feist (n.): also fist, "a breaking wind, foul smell, fart," mid-15c. (Old English had present participle fisting), a general West Germanic word; cf. Middle Dutch veest, Dutch vijst (see feisty).
feisty (adj.): 1896, "aggressive, exuberant, touchy," American English, with -y (2) + feist "small dog," earlier fice, fist (American English, 1805); short for fysting curre "stinking cur," attested from 1520s, from Middle English fysten, fisten "break wind" (mid-15c.); related to Old English fisting "stink," from Proto-Germanic *fistiz- "a fart," said to be from PIE *pezd- (see fart), but there are difficulties.

The 1811 slang dictionary defines fice as "a small windy escape backwards, more obvious to the nose than ears; frequently by old ladies charged on their lap-dogs." Cf. also Danish fise "to blow, to fart," and obsolete English aske-fise, "fire-tender," literally "ash-blower" (early 15c.), from an unrecorded Norse source, used in Middle English for a kind of bellows, but originally "a term of reproach among northern nations for an unwarlike fellow who stayed at home in the chimney corner" [OED].
feldspar (n.): 1785, earlier feldspath (1757), from German Feldspath (Modern German Feldspat), from Feld "field" (see field (n.)) + spath "spar, non-metallic mineral, gypsum" (see spar (n.2)); spelling influenced by English spar "mineral."
Felicia: fem. proper name, from Latin felix (genitive felicis) "happy" (see felicity).
felicide (n.): "killing of a cat," 1832, from Latin feles "cat" (see feline) + -cide.
felicitate (v.): 1620s, "to render happy;" 1630s, "to reckon happy;" from Latin felicitatus, past participle of felicitare "to make happy," from felicitas "fruitfulness, happiness," from felix (see felicity). Meaning "congratulate" is from 1630s. Related: Felicitated; felicitating.
felicitation (n.): 1709, noun of action from felicitate. Related: Felicitations.
felicitous (adj.): 1530s (implied in felicitously), from felicity + -ous.
felicity (n.): late 14c., from Old French felicite (14c.) "happiness," from Latin felicitatem (nominative felicitas) "happiness, fertility," from felix (genitive felicis) "happy, fortunate, fruitful, fertile," from Latin root *fe-, equivalent of PIE *dhe(i)- "to suck, suckle, produce, yield" (see fecund).
feline (adj.): 1680s, from Late Latin felinus "of or belonging to a cat," from Latin feles (genitive felis) "cat, wild cat, marten," of uncertain origin. As a noun, from 1861.
Felix: masc. proper name, from Latin felix "happy" (see felicity).
fell (v.1): Old English fællan (Mercian), fyllan (West Saxon) "make fall, cause to fall," also "strike down, demolish, kill," from Proto-Germanic *fallijanan (cf. Old Frisian falla, Old Saxon fellian, Dutch fellen, Old High German fellen, German fällen, Old Norse fella, Danish fælde), causative of *fallan (Old English feallan, see fall (v.)), showing i-mutation. Related: Felled; feller; felling.
fell (adj.): "cruel," late 13c., from Old French fel "cruel, fierce, vicious," from Medieval Latin fello "villain" (see felon). Phrase at one fell swoop is from "Macbeth."
fell (n.1): "rocky hill," c.1300, from Old Norse fiall "mountain," from Proto-Germanic *felzam- "rock" (cf. German Fels "stone, rock"), from PIE root *pel(i)s- "rock, cliff."
fell (v.2): Old English feoll; past tense of fall (v.).
fell (n.2): "skin or hide of an animal," Old English fel, from Proto-Germanic *fellom- (cf. Old Frisian fel, Old Saxon fel, Dutch vel, Old High German fel, German fell, Old Norse fiall, Gothic fill), from PIE *pello- (see film (n.)).
fella (n.): attempt at phonetic spelling of a casual pronunciation of fellow, attested by 1864. Feller, along the same lines, is recorded by 1825.
fellah (n.): "Egyptian peasant," 1743, from Arabic fallah "plowman," from falaha "to till the soil."
fellahin (n.): 1743, plural of Arabic fallah (see fellah).
fellate (v.): 1968, verbal derivative of fellatio. Related: Fellated; fellating.
fellatio (n.): 1887, from Latin fellatus, past participle of fellare "to suck," from PIE root *dhe(i)- (see fecund). The sexual partner performing fellatio is a fellator; if female, a fellatrice or fellatrix.
fellation (n.): 1888, from fellatio + -ion.
felloe (n.): "rim of a spoked wheel," early 15c., from felie (c.1200), from Old English felga, plural of felg "rim of a wheel," from Proto-Germanic *felz- (cf. Old Saxon felga, Middle Dutch velge, Dutch velg, Old High German felga, German Felge).
fellow (n.): c.1200, from Old English feolaga "fellow, partner," from Old Norse felagi, from fe "money" (see fee) + verbal base denoting "lay" (see lay (v.)). Sense is of "one who puts down money with another in a joint venture." Used familiarly since mid-15c. for "man, male person," but not etymologically masculine.

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. First record of fellow-traveler in sense of "one who sympathizes with the Communist movement but is not a party member," is from 1936, translating Russian poputchik. The literal sense is attested in English from 1610s.
fellow-feeling (n.): 1610s, an attempt to translate Latin compassio and Greek sympatheia. It yielded a back-formed verb, fellow-feel in 17c.
fellowship (n.): c.1200, feolahschipe "companionship," from fellow + -ship. In Middle English it was at times a euphemism for "sexual intercourse" (carnal fellowship).
felo-de-se (n.): Latin, "suicide," literally "one guilty concerning himself."
felon (n.): late 13c., from Old French felon "evil-doer, scoundrel, traitor, rebel, the Devil" (9c.), from Medieval Latin fellonem (nominative fello) "evil-doer," of uncertain origin, perhaps from Frankish *fillo, *filljo "person who whips or beats, scourger" (cf. Old High German fillen "to whip"); or from Latin fel "gall, poison," on the notion of "one full of bitterness."

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.
felonious (adj.): mid-15c. (implied in feloniously), from felony + -ous. Replaced felonous (mid-14c.) by c.1600. Felonly (c.1300) was another variation.
felony (n.): late 13c. as a term in common law, in Anglo-French, from Old French felonie (12c.) "wickedness, evil, treachery, perfidy, crime, cruelty, sin," from Gallo-Romance *fellonia, from fellonem (see felon).
felsic (adj.): 1912, from feldspar + silica + -ic.
felt (n.): Old English felt, from West Germanic *feltaz "something beaten, compressed wool" (cf. Old Saxon filt, Middle Dutch vilt, Old High German filz, German Filz, Danish filt), from Proto-Germanic *felt- "to beat," from PIE *pel- "to thrust, strike, drive" (cf. Old Church Slavonic plusti), with a sense of "beating" (see pulse (n.1)).
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.).