Online Etymology Dictionary

fidget (n.): 1670s, as the fidget "uneasiness," later the fidgets, from a 16c. verb fidge "move restlessly," perhaps from Middle English fiken "to fidget, hasten," from Old Norse fikjask "to desire eagerly" (cf. German ficken "to move about briskly;" see fuck).
fidget (v.): 1670s (implied in fidgetting); see fidget (n.). Related: Fidgeted.
fidgety (adj.): 1730s, from fidget (n.) + -y (2).
fiducial (adj.): 1570s, from Latin fiducialis "reliable," from fiducia "trust" (see faith).
fiduciary (adj.): 1630s, from Latin fiduciarius "(holding) in trust," from fiducia "trust" from root of fidere "to trust" (see faith). In Roman law, fiducia was "a right transferred in trust;" paper currency sense (1878) is because its value depends on the trust of the public. As a noun, from 1630s.
fie (interj.): late 13c., possibly from Old French fi, exclamation of disapproval, and reinforced by a Scandinavian form (cf. Old Norse fy); it's a general sound of disgust that seems to have developed independently in many languages.
fief (n.): also feoff, 1610s, from French fief (12c.) "possession, holding, domain," a variant of Old French fieu "fee" (see fee).
fiefdom (n.): 1814, from fief + -dom.
field (n.): Old English feld "plain, open land" (as opposed to woodland), also "a parcel of land marked off and used for pasture or tillage," probably related to Old English folde "earth, land," from Proto-Germanic *felthuz "flat land" (common West Germanic, cf. Old Saxon and Old Frisian feld "field," Old Saxon folda "earth," Middle Dutch velt, Dutch veld Old High German felt, German Feld "field," but not found outside it; Swedish fält, Danish felt are borrowed from German), from PIE *pel(e)-tu-, from root *pele- (2) "flat, to spread" (see plane (n.1)).

Finnish pelto "field" is believed to have been adapted from Proto-Germanic. The English spelling with -ie- probably is the work of Anglo-French scribes (cf. brief, piece). Collective use for "all engaged in a sport" (or, in horseracing, all but the favorite) is 1742; play the field "avoid commitment" (1936) is from notion of gamblers betting on other horses than the favorite. Field glasses attested by 1836.
field (v.): "to go out to fight," 16c., from field (n.) in the specific sense of "battlefield" (Old English). The meaning "to stop and return the ball" is first recorded 1823, originally in cricket; figurative sense is from 1902. Related: Fielded; fielding.
field day (n.): 1747, originally a day of military exercise and review (see field (v.)); figurative sense is from 1827.
fielder (n.): early 14c., "one who works in a field," agent noun from field (n.). Sporting sense is from 1832 (in cricket; by 1868 in baseball).
fielding (n.): 1823 in cricket (by 1884 in baseball), verbal noun from field (v.).
fieldstone (n.): 1797, from field (n.) + stone (n.).
fiend (n.): Old English feond "enemy, foe," originally present participle of feogan "to hate," from Proto-Germanic *fijæjan (cf. Old Frisian fiand "enemy," Old Saxon fiond, Middle Dutch viant, Dutch vijand "enemy," Old Norse fjandi, Old High German fiant, Gothic fijands), from PIE root *pe(i)- "to blame, revile" (cf. Gothic faian "to blame;" see passion).

As spelling suggests, it was originally the opposite of friend, but the word began to be used in Old English for "Satan" (as the "enemy of mankind"), which shifted its sense to "diabolical person" (early 13c.). The old sense of the word devolved to foe, then to the imported word enemy. For spelling with -ie- see field. Meaning "devotee (of whatever is indicated)," e.g. dope fiend, is from 1865.
fiendish (adj.): 1520s, from fiend + -ish. Related: Fiendishly; fiendishness.
fierce (adj.): mid-13c., "proud, noble, bold," from Old French fers, nominative form of fer, fier "strong, overwhelming, violent, fierce, wild; proud, mighty, great, impressive" (Modern French fier "proud, haughty"), from Latin ferus "wild, untamed," from PIE root *ghwer- "wild, wild animal" (cf. Greek ther, Old Church Slavonic zveri, Lithuanian zveris "wild beast").

Original English sense of "brave, proud" died out 16c., but caused the word at first to be commonly used as an epithet, which accounts for the rare instance of a French word entering English in the nominative case. Meaning "ferocious, wild, savage" is from c.1300. Related: Fiercely; fierceness.
fieri facias: writ concerning a sum awarded in judgment (often requiring seizure and sale of property for debt), Latin, literally "cause it to be done," the first words of the writ.
fiery (adj.): late 13c., from Middle English fier "fire" (see fire (n.)) + -y (2). The spelling is a relic of one of the attempts to render Old English "y" in fyr in a changing system of vowel sounds. Related: Fieriness.
fiesta (n.): 1844, Spanish, literally "feast" (see feast (n.)).
FIFA: 1915, acronym from Fédération Internationale de Football Association, founded 1904 in Paris.
fife (n.): 1550s, from German Pfeife "fife, pipe," from Old High German pfifa, or via Middle French fifre (15c.) from the same Old High German word; ultimately imitative. German musicians provided music for most European courts in those days. As a verb from 1590s. Agent noun fifer is recorded earlier (1530s). Fife and drum is from 1670s.
fifteen (n.): Old English fiftyne, from fif "five" (see five) + tyne (see -teen). Cf. Old Saxon fiftein, Old Frisian fiftine, Old Norse fimtan, Swedish femton, Dutch vijftien, German fünfzehn, Gothic fimftaihun "fifteen." French quinze, Italian quindici "fifteen" are from Latin quindecim (see Quatorze).
fifteenth (adj.): late 14c., from fifteen + -th. By 15c. displacing forms derived from Old English fifteoða. Cf. Old Frisian fiftuda, Dutch vijftiende, German fünfzehnte, Old Norse fimmtandi, Gothic fimftataihunda.
fifth (adj.): c.1200, fift, from Old English fifta, from fif "five" (see five) + -ta (see -th). Altered 14c. by influence of fourth. Cf. Old Frisian fifta, Old Saxon fifto, Old Norse fimmti, Dutch vijfde, Old High German fimfto, German fünfte, Gothic fimfta.

Noun meaning "fifth part of a gallon of liquor" is first recorded 1938, American English. Fifth Avenue (in New York City) has been used figuratively for "elegance, taste" since at least 1858. Fifth wheel "superfluous person or thing" first attested 1902. Fifth-monarchy-man, 17c. for "anrachist zealot," is a reference to Dan. ii:44.
fifth column (n.): 1936, from Gen. Emilio Mola's comment at the siege of Madrid during the Spanish Civil War that he would take the city with his four columns of troops outside it and his "fifth column" (quinta columna) in the city.
fifties (n.): 1826 as the years of someone's life between 50 and 59; 1853 as a decade of years in a given century. See fifty.
fiftieth (adj.): Old English fiftigoða; see fifty + -th. Cf. Old Norse fimmtugande, and, with a different suffix, Old Frisian fiftichsta, Dutch vijftigste, Old High German fimfzugsto, German fünfzigste.
fifty (n.): Old English fiftig, from fif "five" (see five) + -tig "group of ten" (see -ty (1)). Cf. Old Frisian fiftich, Old Norse fimm tigir, Dutch vijftig, Old High German fimfzug, German fünfzig, Gothic fimf tigjus. U.S. colloquial fifty-fifty "in an even division" is from 1913.
fig (n.): early 13c., from Old French figue (12c.), from Old Provençal figa, from Vulgar Latin *fica, from Latin ficus "fig tree, fig," from a pre-Indo-European Mediterranean language, possibly a Semitic one (cf. Phoenician pagh "half-ripe fig"). A reborrowing of a word that had been taken directly from Latin as Old English fic.

The insulting sense of the word in Shakespeare, etc. (A fig for ...) is 1570s, in part from fig as "small, valueless thing," but also from Greek and Italian use of their versions of the word as slang for "cunt," apparently because of how a ripe fig looks when split open [Rawson, Weekley]. Giving the fig (French faire la figue, Spanish dar la higa) was an indecent gesture of ancient provenance, made by putting the thumb between two fingers or into the mouth, with the intended effect of the modern gesture of "flipping the bird" (see bird (n.3)). See sycophant. Use of fig leaf in figurative sense of "flimsy disguise" (1550s) is from Gen. iii:7.
fight (v.): Old English feohtan "to fight" (class III strong verb; past tense feaht, past participle fohten), from Proto-Germanic *fekhtanan (cf. Old High German fehtan, German fechten, Middle Dutch and Dutch vechten, Old Frisian fiuhta "to fight"), from PIE *pek- "to pluck out" (wool or hair), apparently with a notion of "pulling roughly" (cf. Greek pekein "to comb, shear," pekos "fleece, wool;" Persian pashm "wool, down," Latin pectere "to comb," Sanskrit paksman- "eyebrows, hair").

Spelling substitution of -gh- for a "hard H" sound was a Middle English scribal habit, especially before -t-. In some late Old English examples, the middle consonant was represented by a yogh. To fight back "resist" is recorded from 1890.
fight (n.): Old English feohte, gefeoht "a fight;" see fight (v.). Cf. Old Frisian fiucht, Old Saxon fehta, Dutch gevecht, Old High German gifeht, German Gefecht.
fighter (n.): Old English feohtere; agent noun from fight (v.). Cf. German Fechter. Meaning "fast military airplane used for combat" is from 1917.
fighting (adj.): present participle adjective from fight (v.). Fighting chance is from 1877; fighting mad is attested by 1750.
figment (n.): early 15c., from Latin figmentum "something formed or fashioned, creation," related to figura "shape" (see figure (n.)).
figurative (adj.): late 14c., from Old French figuratif "metaphorical," from Late Latin figurativus, from figurat-, past participle stem of figurare "to form, shape," from figura "a shape, form, figure" (see figure (n.)). Of speech, language, etc., "involving figures of speech," from 1845. Related: Figuratively.
figure (v.): late 14c., "to represent" (in a picture); see figure (n.). Meaning "to shape into" is early 15c.; "to picture in the mind" is from c.1600; "to make an appearance" is c.1600. Meaning "work out a sum" is from 1833, American English. Related: Figured; figuring.
figure (n.): early 13c., "visible form or appearance of a person," from Old French figure (10c.) "shape, body, form, figure; symbol, allegory," from Latin figura "a shape, form, figure," from PIE *dheigh- "to form, build" (see dough); originally in English with meaning "numeral," but sense of "form, likeness" is almost as old (mid-13c.).

Philosophical and scientific senses are from Latin figura being used to translate Greek skhema. The rhetorical use of figure dates to late 14c.; hence figure of speech (1824). Figure eight as a shape was originally figure of eight (c.1600).
figurehead (n.): 1765, from figure (n.) + head (n.). Originally the ornament on the bow of a ship; sense of "leader without real authority" is first attested 1883.
figurine (n.): 1854, from French figurine (16c.), from Italian figurina, diminutive of figura, from Latin figura (see figure (n.)).
filament (n.): 1590s, from Modern Latin filamentum, from Late Latin filare "to spin, draw out in a long line," from Latin filum "thread" (see file (v.)).
filbert (n.): "hazelnut," late 14c., from Anglo-French philber (late 13c.), from Norman dialect noix de filbert, in reference to St. Philbert, 7c. Frankish abbot, so called because the hazel nuts ripen near his feast day, Aug. 22 (Old Style). Weekley compares German Lambertsnuss "filbert," associated with St. Lambert (Sept. 17); also German Johannisbeere "red currant," associated with St. John's Day (June 24). The name is Old High German Filu-berht, literally "very bright."
filch (v.): "steal," 1560s, slang, perhaps from c.1300 filchen "to snatch, take as booty," of unknown origin. Liberman says filch is probably from German filzen "comb through." Related: Filched; filching.
filcher (n.): 1570s, agent noun from filch.
file (v.): "to place (papers) in consecutive order for future reference," mid-15c., from Middle French filer "string documents on a wire for preservation or reference," from fil "thread, string" (12c.), from Latin filum "a thread, string," from PIE *gwhis-lom (cf. Armenian jil "sinew, string, line," Lithuanian gysla "vein, sinew," Old Church Slavonic zila "vein"), from root *gwhi- "thread, tendon." The notion is of documents hung up on a line.
File (filacium) is a threed or wyer, whereon writs, or other exhibits in courts, are fastened for the better keeping of them. [Cowel, "The Interpreter," 1607]
Methods have become more sophisticated, but the word has stuck. Related: Filed; filing.
file (n.2): metal tool, Old English feol (Mercian fil), from Proto-Germanic *finkhlo (cf. Old Saxon and Old High German fila, Middle Dutch vile, Dutch vijl, German Feile), probably from PIE *peig- "to cut, mark by incision" (see paint (v.)). The verb in this sense is from early 13c., from Old English filian. Related: Filed; filing.
file (n.1): 1520s, "string or wire on which documents are strung," from French file "row," from Middle French filer (see file (v.)). The meaning "arranged collection of papers" is from 1620s; computer sense is from 1954. The military sense "line or row of men" (1590s) is from the French verb in the sense of "spin out (thread); march in file."
filet (n.): 1841 in cookery, reborrowing from French of the same word that had been taken 14c. and anglicized as fillet (q.v.). Filet mignon is attested as a French word in English from 1815.
The 'Chateaubriand,' the 'entrecôte,' and the 'filet mignon' (of mutton), with other forms, are all due to the more enlarged sympathies of the French butcher for what is perfect. We must entirely change the mode of cutting up the carcase before we can arrive at the same perfection in form of meat purchasable, and as that is hopeless, so is it useless to insist further on the subject on behalf of the public. ["The Kitchen and the Cellar," "Quarterly Review," April 1877]
filial (adj.): late 14c., from Middle French filial, from Late Latin filialis "of a son or daughter," from Latin filius "son," filia "daughter," possibly from a suffixed form of PIE root *bheue- "to be, exist, grow" (see be), though *dhe(i)- "to suck, suckle" (see fecund) "is more likely" [Watkins].
filiation (n.): 1520s, from French filiation, from Medieval Latin filiationem (nominative filiatio), noun of action from filiare "to have a child," from Latin filius/filia (see filial).