Online Etymology Dictionary

flirtation: 1718, from flirt + -tion.
flirtatious: 1834, from flirtation + -ous. Related: Flirtatiously; flirtatiousness.
flirty: 1840, from flirt + -y (2). Related: Flirtiness.
flit: c.1200, flutten "convey, move, take," perhaps from O.N. flytja "cause to fit," from P.Gmc. *flotojan (see float).
"Theire desire ... is to goe to theire newe masters eyther on a Tewsday, or on a Thursday; for ... they say Munday flitte, Neaver sitte." [1641]
Related: Flitted; flitting.
flitch: "side of bacon," M.E. flicche, from O.E. flicce, related to O.N. flikki, M.L.G. vlicke "piece of flesh." Not connected to flesh. A flitch was presented every year at Dunmow, in Essex, to any married couple who could prove they had lived together without quarreling for a year and a day, a custom mentioned as far back as mid-14c.
flitter: 1540s, from flit with frequentative suffix. Flitter-mouse (1540s) is occasionally used in English, in imitation of Ger. fledermaus "bat," from O.H.G. fledaron "to flutter."
flitty: 1640s, from flit + -y (2). Related: Flittiness.
flivver: "cheap car," especially "Model-T Ford," 1910, of unknown origin.
float: O.E. flotian "to float" (class II strong verb; past tense fleat, pp. floten), from P.Gmc. *flutojanan (cf. O.N. flota, M.Du. vloten). Related: Floated; floating. The noun is attested from early 12c., "state of floating" (O.E. flot meant "body of water"); meaning "platform on wheels used for displays in parades, etc." is from 1888, probably from earlier sense of "flat-bottomed boat" (1557). Floater "dead body found in water" is 1890, U.S. slang.
floatation: 1806, the older, more etymological, but less popular spelling of flotation.
floc: 1921, dim. of flocculus (see flocculate).
floccinaucinihilipilification: "action or habit of estimating as worthless," 1741, a combination of four Latin words (flocci, nauci, nihili, pilifi) all signifying "at a small price" or "for nothing," which were listed together in a rule of the well-known Eton Latin Grammar. The kind of jocular formation that was possible among educated men in Britain in those days. Just so, as in praesenti, the opening words of mnemonic lines on conjugation in Lilley's 16c. Latin grammar, could stand alone as late as 19c. and be understood to mean "rudiments of Latin."
flocculate (v.): 1877, from flocculus (1799, from Mod.L., dim. of L. floccus "flock of wool") + -ate. Related: Flocculated; flocculating.
flocculation: 1885, from flocculate + -tion.
flocculent: 1800, from L. floccus "flock of wool" + -ulent.
flock (n.): O.E. flocc "a group of persons," related to O.N. flokkr "crowd, troop, band," M.L.G. vlocke "crowd, flock;" not found in other Gmc. languages, perhaps related to folc "people," but the metathesis would have been unusual for O.E. Extended c.1200 to "a number of animals of one kind moving or feeding together;" of domestic animals c.1300. Transferred to bodies of Christians, in relation to Christ or their local pastor, from mid-14c. The verb meaning "to gather, congregate" is from c.1300. Related: Flocked; flocking.
floe: 1817, first used by Arctic explorers, probably from Norw. flo "layer, slab," from O.N. flo, related to first element in flagstone (q.v.). Earlier explorers used flake.
flog: 1670s, slang, perhaps a schoolboy shortening of L. flagellare "flagellate." Related: Flogged; flogging.
flood (n.): O.E. flod "a flowing of water, river, sea, flood," from P.Gmc. *flothuz (cf. O.Fris. flod, O.N. floð, M.Du. vloet, Ger. Flut, Goth. fiodus), from PIE verbal stem *plo-/*pleu- "flow, float" (cf. Gk. ploein "to float, swim," plotos "floating, navigable"). The verb is first attested 1660s. Related: Flooded; flooding. Flood plain (also floodplain) is from 1873.
floodgate: early 13c. in the figurative sense (especially with reference to tears or rain); literal sense is mid-15c.; from flood + gate.
floor (n.): O.E. flor "floor," from P.Gmc. *floruz "floor" (cf. M.Du. vloer, O.N. flor "floor," M.H.G. vluor, Ger. Flur "field, meadow"), from PIE *plaros (cf. Welsh llawr "ground"), enlarged from *pele- "flat, to spread." The verbal sense of "puzzle, confound" is 1830, from notion of "knock down to the floor" (1640s). Related: Floored; flooring. The figurative sense in legislative assemblies is first recorded 1774. Floor plan attested from 1867.
floozie (n.): also floozy, "woman of disreputable character," 1902, perhaps a variation of flossy "fancy, frilly" (1890s slang), with the notion of "fluffiness."
flop: c.1600, probably a variant of flap with a duller, heavier sound. Sense of "fall or drop heavily" is 1836, that of "collapse, fail" is 1919; though the figurative noun sense of "a failure" is recorded from 1893. The noun in the literal sense is from 1823.
flophouse: "cheap hotel," hobo slang, 1923, from earlier slang flop (v.) "lie down for sleep" (1907); see flop.
floppy disc: attested from 1972.
flora: 1777, "the plant life of a region or epoch," from L. Flora Roman goddess of flowers, from flos (gen. floris) "flower," from *flo-s-, Italic suffixed form of PIE *bhle- extended form of *bhel- (3) "to thrive, bloom," possibly identical with *bhel- (2) "to blow, swell" (see bole). Used as the title of descriptive plant catalogues since 1640s, but popularized by Linnaeus in his 1745 study of Swedish plants, "Flora Suecica."
floral: 1640s, from Fr. floral, from L. floralis "of flowers" (see flora).
Florence: fem. proper name, from L. Florentia, fem. of Florentius, lit. "blooming," from florens (gen. florentis), prp. of florere "to flower" (see flourish). The c.1700 "Dictionary of the Canting Crew" defines Florence as a slang word for "a Wench that is touz'd and ruffled." This was also the Italian city name (Roman Colonia Florentia, "flowering colony," either literal or figurative), which became in O.It. Fiorenze, in modern It. Firenze.
Florentine: 1540s, originally "of or pertaining to the Italian city of Florence," from L. Florentinus.
florescence: 1793, from L. florescentem (nom. florescens) "blooming," prp. of florescere "to begin to bloom," inceptive of florere "to blossom" (see flourish).
florescent: 1821, from L. florescentem, prp. of florescere (see florescence).
floret: 1583, from O.Fr. florete, dim. of flor "flower," from L. flora (q.v.).
florid: 1640s, "strikingly beautiful," from Fr. floride "flourishing," from L. floridus "flowery, blooming," from flos "flower" (see flora). Sense of "ruddy" is first recorded 1640s. Meaning "profusely adorned, as with flowers," is from 1650s.
Florida: U.S. state, formerly a Sp. colony, probably from Sp. Pascua florida, lit. "flowering Easter," a Sp. name for Palm Sunday, because the peninsula was discovered on that day (March 20, 1513) by the expedition of Sp. explorer Ponce de León.
florin: c.1300, from O.Fr. florin, from It. fiorino, from fiore "flower," from L. florem "flower" (see flora). The 13c. gold Florentine coin was stamped on the obverse with the image of a lily, the symbol of the city.
florist: 1620s, formed on analogy of Fr. fleuriste, from L. floris, gen. of flos "flower" (see flora).
floruit: used now mainly in sense of "period during which a historical person's life work was done," 1843, from L., lit. "he flourished," third person singular perf. indic. of florere (see flourish). Usually in abbreviation fl.
floss (n.): "rough silk," 1759, from Fr. floche "tuft of wool," from floc, from L. floccus "tuft of wool." Or from an unrecorded O.E. or O.N. word from the root of Du. flos "plush" (17c.). In "The Mill on the Floss" the word Floss is the proper name of a fictitious river in the Eng. Midlands.
flotation: 1850s, from float + -ation. Spelling influenced by French (cf. floatation).
flotilla: 1711, "a small fleet," from Sp. flotilla, dim. of flota "float," from flotar "to float," of Gmc. origin (see float).
flotsam: c.1600, from Anglo-Fr. floteson, from O.Fr. flotaison "a floating," from floter "to float" (of Gmc. origin) + -aison, from L. -ation(em). Spelled flotsen till mid-19c. when it altered, perhaps under influence of many English words in -some. In British law, flotsam are goods found floating on the sea as a consequence of a shipwreck or action of wind or waves; jetsam are things cast out of a ship in danger of being wrecked, and afterward washed ashore, or things cast ashore by the sailors. Whatever sinks is lagan.
flounce (v.): 1540s, "to dash, plunge, flop," perhaps from Scandinavian (cf. dialectal Swed. flunsa "to plunge," Norw. flunsa "to hurry," but first record of these is 200 years later than the English word), said to be of imitative origin. Spelling likely influenced by bounce. Sense of "anger, impatience" began to adhere to the word 18c. Related: Flounced; flouncing. As a noun, from 1580s.
flounce (n.): "wide ruffle," 1713, from M.E. frounce "pleat, wrinkle, fold" (late 14c.), from O.Fr. fronce "fold, gather, wrinkle," from Frankish *hrunkja "wrinkle," of unknown origin. Influenced in form by flounce (v.).
flounder (v.): 1590s, perhaps an alteration of founder (q.v.), influenced by Du. flodderen "to flop about," or native verbs in fl- expressing clumsy motion. Related: Floundered; floundering.
flounder (n.): "flatfish," c.1304, from Anglo-Fr. floundre, from O.N.Fr. flondre, from O.N. flydhra, related to M.L.G. vlundere, cognate with Gk. platys "flat, wide, broad" (see place (n.)).
flour: early 13c., flur "flower," in the sense of flour being the "finest part" of meal (cf. Fr. fleur de farine). Spelled flower until flour became the accepted form c.1830 to end confusion. See flower.
flourish: c.1300, "to blossom, grow," from O.Fr. floriss-, stem of florir, from L. florere "to bloom, blossom, flower," from flos "a flower" (see flora). Metaphoric sense of "thrive" is mid-14c. Meaning "to brandish (a weapon)" first attested late 14c. Related: Flourished; flourishing. The noun meaning "literary or rhetorical embellishment" is from c.1600.
flout: 1550s, perhaps a special use of M.E. flowten "to play the flute" (cf. M.Du. fluyten "to play the flute," also "to jeer"). Related: Flouted; flouting.
flow (v.): O.E. flowan (class VII strong verb; past tense fleow, pp. flowen), from P.Gmc. *flo- (cf. Du. vloeien "to flow," O.N. floa "to deluge," O.H.G. flouwen "to rinse, wash"), probably from PIE *pleu- "flow, float" (cf. Skt. plavate "navigates, swims," plavayati "overflows;" Armenian helum "I pour;" Gk. plyno "I wash," pleo "swim, go by sea;" L. pluere "to rain;" O.C.S. plovo "to flow, navigate;" Lith. pilu "to pour out," plauti "rinse"). The weak form predominated from 14c., but strong pp. flown is occasionally attested through 18c. Related: Flowed; flowing.
flower (n.): c.1200, from O.Fr. flor, from L. florem (nom. flos) "flower" (see flora), from PIE base *bhlo- "to blossom, flourish" (cf. M.Ir. blath, Welsh blawd "blossom, flower," O.E. blowan "to flower, bloom"). Modern spelling is 14c. Ousted O.E. cognate blostm (see blossom). Also used from 13c. in sense of "finest part or product of anything." The verb is first recorded early 13c. Related: Flowered; flowering. Flower children "gentle hippies" is from 1967.