Online Etymology Dictionary

firefighter (n.): also fire-fighter, 1895, from fire (n.) + fighter.
firefly (n.): also fire-fly, "An insect which has the faculty of becoming luminous" [Century Dictionary], 1650s, from fire (n.) + fly (n.).
firelight (n.): also fire-light, "light emitted by an open fire," Old English fyrleoht; see fire (n.) + light (n.).
firelock (n.): type of gun lock that uses sparks to ignite the priming, 1540s, from fire (n.) + lock (n.). Originally of the wheel-lock; transferred 17c. to the flintlock.
fireman (n.): also fire-man, late 14c., "tender of a fire," from fire (n.) + man (n.). From 1650s as "furnace-tender" of a early steam engine. As "person hired to put out (rather than tend) fires" it is attested from 1714. For "stoker," Old English had fyrbeta.
fireplace (n.): also fire-place, c. 1700, from fire (n.) + place (n.).
fireplug (n.): also fire-plug, 1713, from fire (n.) + plug (n.).
firepower (n.): also fire-power "effectiveness of military fire," 1891, from fire (n.) + power (n.).
fireproof (adj.): also fire-proof, 1630s, from fire (n.) + proof. As a verb, from 1867. Related: Fireproofed; fireproofing.
fireside (n.): also fire-side, 1560s, from fire (n.) + side (n.). Symbolic of home life by 1848. As an adjective from 1740s; especially suggesting the intimately domestic.
firestorm (n.): also fire-storm, 1580s, in poetry, from fire (n.) + storm (n.). From 1945 in reality, in reference to nuclear war.
firetrap (n.): also fire-trap, "place at great risk of destruction by fire and with insufficient means of escape," 1882, from fire (n.) + trap (n.).
firewall (n.): also fire-wall, 1851 as a physical wall meant to prevent the spread of fire in a structure, from fire (n.) + wall (n.). Computer sense (originally figurative) is by 1990.
firewater (n.): also fire-water, "alcoholic liquor," 1826, American English, supposedly from speech of American Indians, from fire (n.) + water (n.1).
firewood (n.): also fire-wood, late 14c., from fire (n.) + wood (n.).
fireworks (n.): also fire-works, "pyrotechnic contrivances," 1570s, from fire (n.) + works. Figurative use from 1660s.
firing (n.): 1540s, "action of applying fire or setting on fire," verbal noun from fire (v.). From c. 1600 as "act of discharging firearms." Firing squad is attested from 1891 in reference to military executions; earlier as "those selected to fire over the grave of anyone interred with military honors" (1864); earlier in both senses is firing-party (1798 in reference to military executions; 1776 in reference to military funerals).
firkin (n.): "small cask," late 14c., apparently from Middle Dutch *vierdekijn, diminutive of vierde, literally "fourth, fourth part" (see fourth); so called because it usually is the fourth part of a barrel.
firm (adj.): late 14c., ferm, "strong, steady" (of things), "permanent, enduring" (of agreements), "steadfast, steady" (of persons), "sound, well-founded" (of arguments), from Old French ferm "strong, vigorous; healthy, sound; steadfast, loyal, faithful" (12c.), from Latin firmus "strong, steadfast, enduring, stable," figuratively "constant, steadfast, trusty, faithful," from PIE root *dher- (2) "to hold, support" (source also of Sanskrit dharmah "custom, law," Greek thronos "seat," Lithuanian dirzmas "strong," Welsh dir "hard," Breton dir "steel"). The spelling return to -i- in late 1500s was modeled on Latin. Related: Firmly; firmness.
firm (n.): "business house," 1744, according to Barnhart from German Firma "a business, name of a business," originally "signature," from Italian firma "signature," from firmare "to sign," from Latin firmare "make firm, affirm," in Late Latin, "confirm (by signature)," from firmus "strong; stable," figuratively "constant, trusty" (see firm (adj.)).
firm (v.): c. 1300, fermen "make firm, establish," from Old French fermer "consolidate; fasten, secure; build, set up; fortify" (12c.) or directly from Latin firmare "make firm; affirm; strengthen, fortify, sustain; establish, prove, declare," from firmus "strong, steadfast, stable" (see firm (adj.)). Intransitive use, "become firm" is from 1879; with up (adv.) from 1956. Related: Firmed; firming.
firmament (n.): mid-13c., from Old French firmament or directly from Latin firmamentum "firmament," literally "a support, a strengthening," from firmus "strong, steadfast, enduring" (see firm (adj.)). Used in Late Latin in the Vulgate to translate Greek stereoma "firm or solid structure," which translated Hebrew raqia, a word used of both the vault of the sky and the floor of the earth in the Old Testament, probably literally "expanse," from raqa "to spread out," but in Syriac meaning "to make firm or solid," hence the erroneous translation. Related: Firmamental.
firmware (n.): 1968, from firm (adj.) + ending from software.
firn (n.): "consolidated snow, the raw material of glaciers," 1839, literally "last year's snow, névé," from German Firn, from Swiss dialectal firn "of last year," from Middle High German virne "old," from Old High German firni, related to Old English fyrn "old," Gothic fairns "of last year," from Proto-Germanic *fur- "before" (see fore (adv.)).

The only living English relic of a useful word meaning "of last year" that was widespread in Indo-European languages (cognates: Lithuanian pernai "last year" (adv.), Greek perysi "a year ago, last year," Sanskrit parut "of last year;" also German Firnewein "wine of last year"). Old English had fyrngemynd "ancient history," more literally, "memory of long ago;" fyrnmann "man of old times;" fyrnnes "antiquity;" fyrnsægen "old saying." Middle English retained fern "long ago, formerly, of old," fern-days "days of old, former year, a year past."
first (n.): 1560s, "that which is first," from first (adj.). Meaning "first day of the month" is by 1590s. In music, "instrument or voice that takes the highest or chief part of its class," 1774. From 1909 as the name of the lowest gear in an engine. In British schools colloquial use, "highest rank in an examination," 1850.
first (adj., adv.): Old English fyrst "foremost, going before all others; chief, principal," also (though rarely) as an adverb, "at first, originally," superlative of fore; from Proto-Germanic *furista- "foremost" (source also of Old Saxon fuirst "first," Old High German furist, Old Norse fyrstr, Danish første, Old Frisian ferist, Middle Dutch vorste "prince," Dutch vorst "first," German Fürst "prince"), from PIE *pre-isto-, superlative of *pre-, from root *per- (1) "forward, through" (see per).

The usual Old English superlative word was not fyrst, but forma, which shows more clearly the connection to fore. Forma became Middle English firme "first, earliest," but this has not survived.

First aid is that given at the scene, pending the arrival of a doctor. First Lady as an informal title for the wife of a U.S. president was in use by 1908, short for First lady of the land (by 1863 with reference to the president's wife); the earlier title was simply Lady (1841). First name is attested from mid-13c. First base "a start" in any sense (1938) is a figurative use from baseball.

First-fruits is from late 14c. as "earliest productions of the soil;" 1590s as "first results" of any activity or endeavor. First love is from 1741 as "one's first experience of romantic love;" 1971 as "one's favorite occupation or pastime." First-floor is from 1660s as "story built on or just above the ground" (now U.S.); 1865 as "story built next above the ground."
first-born (adj., n.): mid-14c., from first (adj.) + born.
first-class (adj.): "of the highest class" with reference to some standard of excellence, 1837, from first (adj.) + class (n.). Specifically in reference to conveyances for travel, 1846. In reference to U.S. Mail, 1875.
first-hand (adj.): also firsthand, "direct from the source or origin," 1690s, from the image of the "first hand" as the producer or maker of something.
first-rate (adj.): "of the highest excellence," 1660s, from first (adj.) + rate (n.) in a specific sense "class of warships in the British Navy." As a mere emphatic statement expressing excellence, by 1812. Colloquially, as a quasi-adverb, 1844.
first-timer (n.): "rookie, one doing something for the first time," 1888, from first time; see first (adj.) + time (n.).
firstly (adv.): "in the first place, before anything else," 1530s, but never a common word (simple first usually serving its place), from first + -ly (2).
firth (n.): "arm of the sea, estuary of a river," early 15c., Scottish, from Old Norse fjörðr (see fjord).
fiscal (adj.): 1560s, "pertaining to public revenue," from Middle French fiscal, from Late Latin fiscalis "of or belonging to the state treasury," from Latin fiscus "state treasury," originally "money bag, purse, basket made of twigs (in which money was kept)," which is of unknown origin. The etymological notion is of the public purse. The general sense of "financial" (1865, American English) was abstracted from phrases fiscal calendar, fiscal year, etc. Related: Fiscally.
fish (n.): Old English fisc "fish," from Proto-Germanic *fiskaz (source also of Old Saxon, Old Frisian, Old High German fisc, Old Norse fiskr, Middle Dutch visc, Dutch vis, German Fisch, Gothic fisks), from PIE *peisk- "fish" (source also of Latin piscis, Irish iasc, and, via Latin, Italian pesce, French poisson, Spanish pez, Welsh pysgodyn, Breton pesk).

Popularly, since Old English, "any animal that lives entirely in the water," hence shellfish, starfish (an early 15c. manuscript has fishes bestiales for "water animals other than fishes"). The plural is fishes, but in a collective sense, or in reference to fish meat as food, the singular fish generally serves for a plural. In reference to the constellation Pisces from late 14c. Fish (n.) for "person" is from 1750 in the faintly dismissive sense; earlier it was used in reference to a person considered desirable to 'catch' (1722). Figurative sense of fish out of water first recorded 1610s. To drink like a fish is from 1744. Fish-story attested from 1819, from the tendency to exaggerate the size of the catch (or the one that got away).
Do not tell fish stories where the people know you; but particularly, don't tell them where they know the fish. [Mark Twain]
To have other fish to fry "other objects which invite or require attention" is from 1650s. Fish-eye as a type of lens is from 1961. Fish-and-chips is from 1876; fish-fingers from 1962. Fish-food is from 1936 as "food for (pet or hobby) fish."
fish (v.): Old English fiscian "to fish, to catch or try to catch fish" (cognates: Old Norse fiska, Old High German fiscon, German fischen, Gothic fiskon), from the root of fish (n.). Related: Fished; fishing.
fish-hook: late 14c., from fish (n.) + hook (n.).
fish-tail (n.): 1840, "the tail of a fish," from fish (n.) + tail (n.). As a verb, also fishtail, 1927, originally of aircraft, later automobiles. Related: Fishtailed; fishtailing.
fish-tank (n.): 1921 as an ornamental object, from fish (n.) + tank (n.).
fisher (n.): Old English fiscere "fisherman; kingfisher," agent noun from fish (v.). It began to be used of certain animals, hence perhaps the rise of the formation fisherman (1520s). Similar formation in Old Saxon fiskari, Old Frisian fisker, Dutch visscher, German Fischer, Old Norse fiskari.
fisherman (n.): 1520s, from fisher + man (n.).
fishery (n.): "business of fishing," 1670s; "place where fish are caught," 1690s; see fish (v.) + -ery. Related: Fisheries.
fishing (n.): "the art or practice of trying to catch fish," c. 1300, fysschynge, verbal noun from fish (v.). Figurative use from 1540s. The Old English noun was fiscað.
[O]f all diversions which ingenuity ever devised for the relief of idleness, fishing is the worst qualified to amuse a man who is at once indolent and impatient. [Scott, "Waverly," 1814]
Fishing-boat is from 1732. Fishing rod (1550s) is older than fishing pole (1791). To "go fishing" is as old as Old English on fiscoð gan.
fishmonger (n.): also fish-monger, mid-15c., from fish (n.) + monger (n.).
fishnet (n.): "net used to catch fish," Old English fiscnett; see fish (n.) + net (n.). From 1881 in reference to a type of stitch that resembles fishnet. By 1912 in reference to women's hosiery.
There has been considerable misconception as to the purpose of the fishnet hose imported by the ECONOMIST and illustrated on page 177. The newspaper representatives who viewed it at the ECONOMIST'S fashion exhibition used it as a pretext for many humorous articles and conveyed the impression that it was to be worn next the skin. The purpose is to use it over white or colored hose, to produce an unusual effect. Every store should have one or more pairs for exhibition purposes, if for no other reason. ["Dry Goods Economist," June 22, 1912]
fishpond (n.): also fish-pond, mid-15c., from fish (n.) + pond (n.).
fishwife (n.): 1520s, from fish (n.) + wife (n.) in the "woman" sense. Also fish-fag.
fishy (adj.): late 15c., "fish-like, slimy," from fish (n.) + -y (2). In reference to taste, from 1540s. Sense of "shady, questionable" is first recorded 1840, perhaps from the notion of "slipperiness," or of giving off a bad odor.
fisk (v.): 2002, an Internet argument tactic involving a reprinting of a text, interlarded with rebuttals and refutations. Named for English journalist Robert Fisk (b.1946), Middle East correspondent for the "Independent," whose writing often criticizes America and Israel and is somewhat noted for looseness with details. Critics responded in this style. Related: Fisked; fisking.
fissile (adj.): 1660s, from Latin fissilis "that which may be cleft or split," from fissus, past participle of findere "cleave, split, separate, divide" (see fissure).