Online Etymology Dictionary

backfire: 1839, Amer.Eng., originally "a fire deliberately lit ahead of an advancing prairie fire to deprive it of fuel," from back + fire (v.). As a verb in this sense, recorded from 1886. The meaning "premature ignition in an internal-combustion engine" is first recorded 1897. Of schemes, plans, etc., "affect the initiator rather than the intended object" it is attested from 1912, a fig. use from the accidental back-firing of firearms.
backgammon: 1640s, baggammon, the second element from M.E. gamen, ancestor of Mod.E. game; the first element because pieces are sometimes forced to go "back." Known 13c.-17c. as tables.
background: 1670s, from back (adj.) + ground; original sense was theatrical, later applied to painting. Figurative sense is first attested 1854.
backhand: as a tennis stroke, 1650s, from back (adj.) + hand. The fig. sense of "indirect" is from c.1800.
backhoe: by 1928, from back + hoe.
backing: 1590s, "support;" 1640s, "retreat;" from back (v.). Physical sense of "anything forming a backing to something else" is from 1793. Meaning "musical accompaniment" is recorded from 1940.
backlash: 1815, of machinery, from back (adj.) + lash. In metaphoric sense, it is attested from 1921.
backlog: 1680s, from back + log. Originally a large log placed at the back of a fire. Figurative sense is first attested 1883, via notion of "a reserve of something stored up."
backpack: 1914 as a noun, 1916 as a verb, from back + pack.
backside: late 15c., from back (adj.) + side. In the specific sense of "rump, buttocks" it is first recorded c.1500.
backslash: 1982, new punctuation symbol introduced for computer purposes, from back (adj.) + slash (n.).
backslide: in the religious sense, 1580s, from back (adj.) + slide.
backstabber: in the fig. sense is from 1906, from back (n.) + stab. Originally in ref. to politicians and the working class in England. The verb backstab in the fig. sense is from 1925.
backstop (n.): 1819, in cricket, from back + stop. In U.S. baseball, from 1889; fig. extension to "catcher on a baseball team" is from 1890. The verb is attested from 1956 in the sense of "support."
backstory: c.1990, from background story.
backtrack: "retrace one's steps," 1904, from back (adj.) + track (v.).
backup: see back up.
backward: c.1300, from abakward, from O.E. on bæc + -weard adj./adv. suffix. Backwards, with adverbial genitive, is from 1510s. Meaning "behindhand with regard to progress" is first attested 1690s. To ring bells backward (from lowest to highest), c.1500, was a signal of alarm for fire or invasion, or to express dismay.
backwards: 1510s, from backward with adverbial genitive. Figurative phrase bend over backwards is recorded from 1925.
backwash: 1876, Motion of a receeding wave," from back + wash.
backwater: late 14c., "water behind a dam," from back + water. Hence flat water without a current near a flowing river, as in a mill race (1820); fig. use of this for any flat, dull place is from 1899.
backyard: 1650s, from back (adj.) + yard (1).
bacon: early 14c., "meat from the back and sides of a pig" (originally either fresh or cured), from O.Fr. bacon, from P.Gmc. *bakkon "back meat" (cf. O.H.G. bahho, O.Du. baken "bacon"). Slang phrase bring home the bacon first recorded 1908; bacon formerly being the staple meat of the working class.
bacteria: 1847, from Mod.L. pl. of bacterium, from Gk. bakterion "small staff," dim. of baktron "stick, rod," from PIE *bak- "staff used for support." So called because the first ones observed were rod-shaped. Introduced as a scientific word 1838 by Ger. naturalist Christian Gottfried Ehrenberg (1795-1876). Related: Bacterial (1871).
bacteriology: 1884, from Ger.; see bacteria.
bacteriophage: 1921, from Fr. bactériophage (1917), from bacterio-, comb. form of bacteria + -phage (see -phagous).
bacterium: c.1848, sing. of see bacteria (q.v.).
Bactrian: type of camel, c.1600, from L. Bactria, ancient region in what is now northwestern Afghanistan, lit. "the western province," from Pers. bakhtar "the west."
bad: c.1200, a mystery word with no apparent relatives in other languages.* Possibly from O.E. derogatory term bæddel and its dim. bædling "effeminate man, hermaphrodite, pederast," probably related to bædan "to defile." Originally "defective, inferior;" sense of "evil, morally depraved" is first recorded c.1300. A rare word before 1400, and evil was more common in this sense until c.1700. Comparable words in the other I.E. languages tend to have grown from descriptions of specific qualities, such as "ugly," "defective," "weak," "faithless," "impudent," "crooked," "filthy" (e.g. Gk. kakos, probably from the word for "excrement;" Rus. plochoj, related to O.C.S. plachu "wavering, timid;" Pers. gast, O.Pers. gasta-, related to gand "stench;" Ger. schlecht, originally "level, straight, smooth," whence "simple, ordinary," then "bad"). Comparative and superlative forms badder, baddest were common 14c.-18c. and used as recently as Defoe (but not by Shakespeare), but yielded to comp. worse and superl. worst (which had belonged to evil and ill). In U.S. place names, sometimes translating native terms meaning "supernaturally dangerous." Ironic use as a word of approval is said to be at least since 1890s orally, originally in Black Eng., emerging in print 1928 in a jazz context. It might have emerged from the ambivalence of expressions like bad nigger, used as a term of reproach by whites, but among blacks sometimes representing one who stood up to injustice, but in the U.S. West bad man also had a certain ambivalence:
"These are the men who do most of the killing in frontier communities, yet it is a noteworthy fact that the men who are killed generally deserve their fate." [Farmer & Henley]
*Farsi has bad in more or less the same sense as the English word, but this is regarded by linguists as a coincidence. The forms of the words diverge as they are traced back in time (Farsi bad comes from M.Pers. vat), and such accidental convergences exist across many languages, given the vast number of words in each and the limited range of sounds humans can make to signify them. Among other coincidental matches with English are Korean mani "many," Chinese pei "pay," Nahuatl (Aztecan) huel "well," Maya hol "hole."
bad-mouth (v.): "abuse someone verbally," 1941, probably ultimately from noun phrase bad mouth (1835), in black Eng., "a curse, spell," translating an idiom found in African and West Indian languages.
badass: "tough guy," 1950s U.S. slang, from bad + ass (2).
badder: obs. comparative of bad (q.v.), common 14c.-18c.
baddest: obs. superlative of bad (q.v.), common 14c.-18c.
bade: O.E. bæd, p.t. of bid (q.v.).
badge: mid-14c., perhaps from Anglo-Fr. bage or from Anglo-L. bagis, pl. of bagia "emblem," all of unknown origin.
badger (n.): 1520s, from M.E. bageard, perhaps from bage "badge" + -ard "one who carries some action or possesses some quality," suffix related to M.H.G. -hart "bold" (see -ard). If so, the central notion is the badge-like white blaze on the animal's forehead (cf. Fr. blaireau "badger," from O.Fr. blarel, from bler "marked with a white spot"). But blaze (2) was the usual word for this. The O.E. name for the creature was the Celtic borrowing brock. In Amer.Eng., the nickname of inhabitants or natives of Wisconsin (1833).
badger (v.): 1794, from badger (n.), based on the behavior of the dogs in the medieval sport of badger-baiting.
badinage: "light railery," 1650s, from Fr. badinage "playfulness, jesting," from badiner (v.) "to jest, joke," from badin "silly, jesting," from O.Prov. badar "to yawn, gape," from L.L. badare "to gape," from *bat-, the root of abash.
badlands: "arid, highly eroded regions of the western U.S.," 1852, from bad + land. Applied to urban districts of crime and vice since 1892 (originally with ref. to Chicago).
badminton: 1874, from Badminton House, name of Gloucestershire estate of the Duke of Beaufort, where the game first was played in England, mid-19c., having been picked up by British officers from Indian poona. The place name is O.E. Badimyncgtun (972), "estate of (a man called) Baduhelm."
Baedeker: "travel guide," 1863, from Ger. printer and bookseller Karl Baedeker (1801-1859) whose popular travel guides began the custom of rating places with one to four stars. The Baedeker raids by the Luftwaffe in April and May 1942 targeted British cultural and historical sites.
baffle (v.): 1540s, "to disgrace," perhaps a Scottish respelling of bauchle "to disgrace publicly" (especially a perjured knight), which is probably related to Fr. bafouer "to abuse, hoodwink" (16c.), possibly from baf, a natural sound of disgust, like bah (cf. Ger. baff machen "to flabbergast"). Meaning "to bewilder, confuse" is from 1640s; that of "to defeat someone's efforts" is from 1675. The noun sense of "shielding device" is first recorded 1881. Related: Baffled "confounded" (1650s); bafflement (1841).
baffling: 1783, "bewildering," from baffle; earlier a sailor's word for winds that blow variously and make headway difficult (c.1770s).
bag: early 13c., bagge, from O.N. baggi or a similar Scandinavian source, perhaps ultimately of Celtic origin. Disparaging slang for "woman" dates from 1924 (though various specialized senses of this are much older). Meaning "person's area of interest or expertise" is 1964, from Black Eng. slang, from jazz sense of "category," probably via notion of putting something in a bag. To be left holding the bag (and presumably nothing else), "cheated, swindled" is attested by 1793. Many fig. senses are from the notion of the game bag (late 15c.) into which the product of the hunt was placed; e.g. the verb meaning "to kill game" (1814) and its colloquial extension to "catch, seize, steal" (1818).
bagatelle: 1630s, "a trifle," from Fr. bagatelle "knicknack, bauble, trinket" (16c.), from It. bagatella "a trifle," dim. of L. baca "berry." As "a piece of light music," it is attested from 1827.
bagel: 1919, from Yiddish beygl, from M.H.G. boug- "ring, bracelet," from O.H.G. boug "a ring," related to O.E. beag "ring" (in poetry, an Anglo-Saxon lord was beaggifa "ring-giver"), from P.Gmc. *baugaz-, from PIE base *bheug- "to bend" (cf. O.H.G. biogan "to bend;" see bow (v.)).
baggage: mid-15c., from O.Fr. bagage "baggage, (military) equipment" (14c.), from bague "pack, bundle, sack," ultimately from the same Scandinavian source that yielded bag.
bagger: 1740, "miser," from bag (q.v.). Of persons who bag various things for a living, from 19c.; meaning "machine that puts things in bags" is from 1896.
baggy (adj.): "puffed out, hanging loosely," 1831, from bag (q.v.).
Baghdad: a pre-Islamic name apparently of Indo-European origin and probably meaning "gift of god," with the first element related to Rus. bog "god" and the second to Eng. donor. Marco Polo (13c.) wrote it Baudac.