Online Etymology Dictionary

forecaster (n.): 1630s, agent noun from forecast (v.).
forecastle (n.): c.1400, earlier Anglo-French forechasteil (mid-14c.), from Middle English fore- "before" + Anglo-French castel "fortified tower," the short raised deck in the fore part of the ship used in warfare (see castle (n.)). Spelling fo'c'sle reflects sailors' pronunciation.
foreclose (v.): late 13c., from Old French forclos, past participle of forclore "exclude" (12c.), from fors "out" (Modern French hors; from Latin foris "outside;" see foreign) + clore "to shut" (see close (v.)). Senses in English influenced by words in for-. Specific mortgage law sense is first attested 1728. Related: Foreclosed; foreclosing.
foreclosure (n.): 1728, from foreclose + -ure.
forefather (n.): "ancestor," c.1300, from fore- + father (n.); perhaps directly from Old Norse forfaðir.
forefinger (n.): mid-15c., from fore- + finger (n.). So called because it is considered the first next to the thumb.
forefront (n.): late 15c., a Germanic-Latin hybrid, from fore- + front (n.). Originally of buildings; the main modern sense is from military meaning "front rank of an army" (1510s).
forego (v.): "to go before," Old English foregan "to go before," from fore- + go. The similarly constructed foredone "killed, destroyed," now is archaic, replaced by done for. Related: Foregoing; foregone.

Phrase foregone conclusion popularized in "Othello" [III.iii], but Shakespeare's sense was not necessarily the main modern one of "a decision already formed before the case is argued." Othello says it of Cassio's dream, and it is clear from the context that Othello means Cassio actually has been in bed with Desdemona before he allegedly dreamed it.
foreground (n.): 1690s, in the landscape sense, from fore- + ground (n.). First used in English by Dryden ("Art of Painting"); cf. Dutch voorgrond.
forehand: tennis stroke, 1879 (adj.), 1909 (n.), from fore- + hand (n.). Earlier it meant "position in front or above" (16c.); hence forehanded "prudent." Earliest use of the word is in archery, forehand shaft "arrow for shooting straight in front" (1540s).
forehead (n.): Old English forheafod, from fore- + heafod (see head (n.)).
foreign (adj.): mid-13c., ferren, foreyne "out of doors," from Old French forain "strange, foreign; outer, external, outdoor; remote, out-of-the-way" (12c.), from Medieval Latin foranus "on the outside, exterior," from Latin foris "outside," literally "out of doors," related to for1s "door," from PIE *dhwor-ans-, from root *dhwer- "door, doorway" (see door). Spelling altered 17c. perhaps by influence of reign, sovereign. Replaced native fremd. Sense of "not in one's own land" is first attested late 14c.
foreigner (n.): early 15c., foreyner; see foreign + -er (1).
In ordinary use chiefly applied to those who speak a foreign language as their native tongue; thus in England the term is not commonly understood to include Americans. [OED]
foreknowledge (n.): 1530s, from fore- + knowledge. Cf. foreknow "to know beforehand" (late 14c.).
foreleg (n.): late 15c., from fore- + leg (n.).
forelock (n.): "lock of hair growing above the forehead," Old English forelocca; see fore- + lock (n.2).
"Opportunity has hair in front, behind she is bald; if you seize her by the forelock, you may hold her; but, if she once escapes, not Jupiter himself can catch her again." ["Dictionary of Latin Quotations, Proverbs, Maxims and Mottos," H.T. Riley, London, 1866]
foreman (n.): 1530s in the sense of "principal juror;" 1570s in the sense of "principal workman;" from fore- + man (n.). Earliest attested meaning (early 13c.) was "a leader." In 17c., a slang word for "penis."
forementioned (adj.): 1580s; see fore- + mention (v.). A verb foremention is attested from 1650s.
foremost (adj.): Old English fyrmest "earliest, first, most prominent," from Proto-Germanic *formo- (related to Old English fruma "beginning"), superlative of the root of fore + additional superlative suffix -est. Cf. -most, and cf. also Old Frisian formest, Gothic frumists. Altered on the assumption that it is a compound of fore and most.
forename (n.): 1530s, from fore- + name (n.). The equivalent of Latin praenomen.
forenoon (n.): c.1500, from fore- + noon.
forensic (adj.): "pertaining to or suitable for courts of law," 1650s, from Latin forensis "of a forum, place of assembly," from forum "public place" (see forum). Used in sense of "pertaining to legal trials," as in forensic medicine (1845). Related: Forensical (1580s).
foreordained (adj.): early 15c., for-ordenede; see fore- + ordain (v.). A hybrid word. Related: Foreordain.
foreplay (n.): in sexual sense, by 1911, from fore- + play (n.). Earlier as a theatrical term (by 1857).
In fact the poem which Mr. Brooks has translated is but the "prologue to the swelling theme," the fore-play to the actual drama of Faust. ["The Christian Examiner and Religious Miscellany," Jan.-May 1857]
forerunner (n.): c.1300, from fore + runner. Middle English rendition of Latin praecursor, in reference to John the Baptist as the forerunner of Christ. The Old English word was foreboda.
foresee (v.): Old English foreseon "have a premonition," from fore- "before" + seon "to see, see ahead" (see see (v.)). Related: Foresaw; foreseeing; foreseen.
foreseeable (adj.): 1804, from foresee + -able. Related: Foreseeably.
foreshadow (v.): 1570s, from fore- + shadow (v.); the notion is of a shadow thrown before an advancing material object as an image of something suggestive of what is to come. Related: Foreshadowed; foreshadowing.
foreshorten (v.): c.1600, from fore- + shorten. Related: Foreshortened; foreshortening.
foresight (n.): c.1300, from fore- + sight (n.). Cf. German Vorsicht.
foreskin (n.): 1530s, from fore- + skin (n.). A loan-translation of Latin prepuce.
forest (n.): late 13c., "extensive tree-covered district," especially one set aside for royal hunting and under the protection of the king, from Old French forest "forest, wood, woodland" (Modern French forêt), probably ultimately from Late Latin/Medieval Latin forestem silvam "the outside woods," a term from the Capitularies of Charlemagne denoting "the royal forest;" perhaps via Old High German forst, from Latin foris "outside" (see foreign), with a sense of "beyond the park," the park being the main or central fenced woodland.

Another theory traces it through Medieval Latin forestis, originally "forest preserve, game preserve," from Latin forum in legal sense "court, judgment;" in other words "land subject to a ban" [Buck]. Replaced Old English wudu.
forest (v.): 1818 (forested is attested from 1610s), from forest (n.).
forestall (v.): late 14c. (implied in forestalling), "to lie in wait for;" also "to intercept goods before they reach public markets and buy them privately" (formerly a crime; mid-14c. in this sense in Anglo-French), from Old English noun foresteall "intervention, hindrance (of justice); an ambush, a waylaying," literally "a standing before (someone)," from fore- "before" + steall "standing position" (see stall (n.1)). Modern sense of "to anticipate and delay" is from 1580s. Related: Forestalled; forestalling.
forester (n.): late 13c. (late 12c. as a surname), from Old French forestier "forest ranger, forest-dweller" (also, as an adjective, "wild, rough, coarse, unsociable"), from forest (see forest (n.)).
forestry (n.): 1690s, "privilege of a royal forest," from Old French foresterie, from forest (see forest). Meaning "science of managing forests" is from 1859.
foretaste (n.): early 15c., from fore- + taste (n.). As a verb, from mid-15c.
foretell (v.): c.1300, from fore- + tell (v.). Related: Foretold; foretelling.
forethought (n.): c.1300, from fore- + thought. Old English had foreðencan "to premeditate, consider."
foretime (n.): 1530s, from fore- + time (n.).
forever (adv.): late 14c., for ever; from for + ever. One word from late 17c.
forewarn (v.): early 14c., from fore- + warn. Related: Forewarned; forewarning.
foreword (n.): 1842, from fore- + word (n.); perhaps a loan-translation of German Vorwort "preface," modeled on Latin praefatio "preface."
forfeit (n.): c.1300, "misdeed," from Old French forfait "crime, punishable offense" (12c.), originally past participle of forfaire "transgress," from for- "outside, beyond" (from Latin foris; see foreign) + faire "to do" (from Latin facere; see factitious). Translating Medieval Latin foris factum. Sense shifted mid-15c. from the crime to the penalty: "something to which the right is lost through a misdeed." As an adjective from late 14c., from Old French forfait.
forfeit (v.): c.1300, "to lose by misconduct;" see forfeit (n.). Related: Forfeited; forfeiting.
forfeiture: mid-14c., from Old French forfaiture "crime, transgression; penalty for committing a crime," from forfait (see forfeit).
forfend (v.): also forefend, late 14c., "to protect, prohibit; to avert, prevent," a hybrid from for- + fend, from Latin defendere "to ward off."
forgave: past tense of forgive (q.v.).
forge (n.): late 14c., "a smithy," from Old French forge (12c.) "forge, smithy," earlier faverge, from Latin fabrica "workshop," from faber (genitive fabri) "workman in hard materials, smith" (see fabric). As the heating apparatus itself, from late 15c.
forge (v.2): 1610s, "make way, move ahead," of unknown origin, perhaps an alteration of force (v.), but perhaps rather from forge (n.), via notion of steady hammering at something. Originally nautical, in reference to vessels.