Online Etymology Dictionary

big mouth (n.): also bigmouth "person who talks too much," 1889, American English, from big + mouth (n.).
big shot (n.): "important person," 1929, American English, from Prohibition-era gangster slang; earlier in the same sense was great shot (1861). Ultimately a reference to large type of gunshot.
big time (n.): "upper reaches of a profession or pursuit," c. 1910 from vaudeville slang; the phrase was common in colloquial use late 19c.-early 20c. in a broad range of senses: "party, shindig, fun, frolic."
big-tent (adj.): in reference to welcoming all sorts and not being ideologically narrow, American English, 1982 with reference to religion, by 1987 with reference to politics.
bigamist (n.): 1630s; see bigamy + -ist. Earlier in the same sense was bigame (mid-15c.), from Old French bigame, from Medival Latin bigamus.
bigamous (adj.): 1690s; see bigamy + -ous.
bigamy (n.): "state of having two wives or husbands at the same time," mid-13c., from Old French bigamie (13c.), from Church Latin bigamia, from Late Latin bigamus "twice married," a hybrid from bi- "double" (see bi-) + Greek gamos "marrying" (see gamete). The Greek word was digamos "twice married."
Bigamie is unkinde ðing, On engleis tale, twie-wifing. [c. 1250]
In Middle English, also of two successive marriages or marrying a widow.
bigass (adj.): also big-ass, big-assed, by 1945, U.S. military slang, from big + ass (2).
bigfoot (n.): supposed elusive man-like creature of the Pacific Northwest, 1963, from big (adj.) + foot (n.).
bigger (adj.): comparative of big.
biggest (adj.): superlative of big.
biggie (n.): 1931, from big + -ie.
bight (n.): Old English byht "bend, angle, corner" (related to bow), from Proto-Germanic *buhtiz (source also of Middle Low German bucht, German Bucht, Dutch bocht, Danish bught "bight, bay"), from PIE root *bheug- (3) "to bend," with derivatives referring to bent, pliable, or curved objects (source also of Old English beag, Old High German boug "ring;" see bow (v.)). Sense of "indentation on a coastline" is from late 15c.
bigness (n.): late 15c., from big + -ness.
bigot (n.): 1590s, "sanctimonious person, religious hypocrite," from French bigot (12c.), which is of unknown origin. Earliest French use of the word is as the name of a people apparently in southern Gaul, which led to the now-doubtful, on phonetic grounds, theory that the word comes from Visigothus. The typical use in Old French seems to have been as a derogatory nickname for Normans, the old theory (not universally accepted) being that it springs from their frequent use of the Germanic oath bi God. But OED dismisses in a three-exclamation-mark fury one fanciful version of the "by god" theory as "absurdly incongruous with facts." At the end, not much is left standing except Spanish bigote "mustache," which also has been proposed but not explained, and the chief virtue of which as a source seems to be there is no evidence for or against it.

In support of the "by God" theory, as a surname Bigott, Bygott are attested in Normandy and in England from the 11c., and French name etymology sources (such as Dauzat) explain it as a derogatory name applied by the French to the Normans and representing "by god." The English were known as goddamns 200 years later in Joan of Arc's France, and during World War I Americans serving in France were said to be known as les sommobiches (see also son of a bitch). But the sense development in bigot is difficult to explain. According to Donkin, the modern use first appears in French 16c. This and the earliest English sense, "religious hypocrite," especially a female one, might have been influenced by beguine and the words that cluster around it. Sense extended 1680s to other than religious opinions.
bigoted (adj.): 1640s, from bigot (q.v.).
bigotry (n.): 1670s, from French bigoterie "sanctimoniousness," from bigot (see bigot).
bigwig (n.): 1731, from big + wig, in reference to the imposing wigs formerly worn by men of rank or authority.
bijou (n.): 1660s, from French bijou, from Breton bizou "(jeweled) ring," from bez "finger" (compare Cornish bisou "finger-ring," 13c.).
bike (n.): 1882, American English, shortened and altered form of bicycle.
biker (n.): "motorcycle rider" (especially with reference to club affiliation), 1968, American English, from bike (n.) in its slang sense of "motorcycle" (1939).
bikini (n.): "low-waisted two-piece women's bathing suit," 1948, from French coinage, 1947, named for U.S. A-bomb test of June 1946 on Bikini, Marshall Islands atoll, locally Pikinni and said to derive from pik "surface" and ni "coconut," but this is uncertain. Various explanations for the swimsuit name have been suggested, none convincingly, the best being an analogy of the explosive force of the bomb and the impact of the bathing suit style on men's libidos (compare c. 1900 British slang assassin "an ornamental bow worn on the female breast," so called because it was very "killing").
Bikini, ce mot cinglant comme l'explosion même ... correspondant au niveau du vêtement de plage à on anéantissement de la surface vêtue; à une minimisation extrême de la pudeur. [Le Monde, 1947]
As a style of scanty briefs, from 1960. Variant trikini (1967), with separate bra cups held on by Velcro, falsely presumes a compound in bi-.
bilabial (adj.): 1857, from bi- + labial. Alternative bilabiate is attested from 1794.
bilateral (adj.): "having two sides," 1775, from bi- + lateral. Related: Bilaterally.
bilateralism (n.): 1852, from bilateral + -ism.
bilbo (n.): kind of sword noted for temper and elasticity, 1590s, from Bilbao, town in northern Spain where swords were made, in English Bilboa. The town name is Roman Bellum Vadum "beautiful ford" (over the Nervion River).
Bildungsroman (n.): 1910, from German Bildungsroman, from Bildung "education, formation, growth" (from Bild "picture, image, figure;" Old High German bilade) + roman "novel" (see romance). A novel set in the formative years, or the time of spiritual education, of the main character.
bile (n.): 1660s, from French bile (17c.) "bile," also, informally, "anger," from Latin bilis "fluid secreted by the liver," also one of the four humors (also known as choler), thus "anger, peevishness" (especially as black bile, 1797).
bilge (n.): 1510s, "lowest internal part of a ship," also used of the foulness which collects there; variant of bulge "ship's hull," also "leather bag," from Old North French boulge "leather sack," from Late Latin bulga "leather sack," apparently from Gaulish bulga (see budget (n.)).
biliary (adj.): "pertaining to bile," 1731, from French biliaire, from bile (see bile). Meaning "bilious in mood or temperament" is recorded from 1837.
bilinear (adj.): also bi-linear, 1851, from bi- + linear. Related: Bilinearly; bilinearity.
bilingual (adj.): 1818, from bi- + lingual. Latin bilinguis meant literally "two-tongued," and, figuratively, "speaking a jumble of languages," also "double-tongued, hypocritical, false."
bilingualism (n.): 1873, from bilingual + -ism.
bilious (adj.): 1540s, "pertaining to bile, biliary," from French bilieux, from Latin biliosus "pertaining to bile," from bilis (see bile). Meaning "wrathful, peevish, ill-tempered" (as people afflicted with an excess of bile were believed to be) is attested from 1560s. This is the main modern sense in English and French; the more literal meaning being taken up by biliary. Related: Biliousness.
bilirubin (n.): "reddish pigment found in bile," 1871, from German bilirubin (1864), from bili- (see bile) + Latin ruber "red" (see red (1)) + -ine (2).
bilk (v.): 1650s, from or along with the noun (1630s), first used as a cribbage term; as a verb, "to spoil (someone's) score." Origin obscure, it was believed in 17c. to be "a word signifying nothing;" perhaps it s a thinned form of balk "to hinder." Meaning "to defraud" is first recorded 1670s. Related: Bilked; bilking.
bill (n.1): "written statement," mid-14c., from Anglo-French bille, Anglo-Latin billa "list," from Medieval Latin bulla "decree, seal, sealed document," in classical Latin "bubble, boss, stud, amulet for the neck" (hence "seal;" see bull (n.2)). Sense of "account, invoice" first recorded c. 1400; that of "order to pay" (technically bill of exchange) is from 1570s; that of "paper money" is from 1660s. Meaning "draft of an act of Parliament" is from 1510s.
bill (n.2): "bird's beak," Old English bill "bill, bird's beak," related to bill, a poetic word for a kind of sword (especially one with a hooked blade), from a common Germanic word for cutting or chopping weapons (compare Old High German bihal, Old Norse bilda "hatchet," Old Saxon bil "sword"), from PIE root *bheie- "to cut, to strike" (source also of Armenian bir "cudgel," Greek phitos "block of wood," Old Church Slavonic biti "to strike," Old Irish biail "ax"). Used also in Middle English of beak-like projections of land (such as Portland Bill).
bill (v.): "to send someone a bill of charge," 1864, from bill (n.1). Related: Billed; billing.
bill (n.3): ancient weapon, Old English bill "sword (especially one with a hooked blade), chopping tool," common Germanic (compare Old Saxon bil "sword," Middle Dutch bile, Dutch bijl, Old High German bihal, German Beil, Old Norse bilda "hatchet." See bill (n.2).
billable (adj.): 1570s, from bill (v.) + -able.
billabong: Australian, "backwater, stagnant pool," 1865, from Billibang, Aboriginal name of Bell River, from billa "water" + bang, of uncertain meaning.
billboard (n.): 1845, American English, from bill (n.1) + board (n.1). Any sort of board where bills were meant to be posted. Billboard magazine founded 1894, originally a trade paper for the bill-posting industry. Its music sales charts date from 1930s.
billet (v.): 1590s, "to assign quarters to," earlier, as a noun, "official record or register" (Middle English), from Anglo-French billette "list, schedule," diminutive of bille (see bill (n.1)) with -let. Related: Billeted; billeting.
billet (n.1): thick stick of wood, mid-15c., from Middle French billette, diminutive of bille "stick of wood" (see billiards).
billet (n.2): "document, note;" see billet-doux.
billet-doux (n.): also billet doux, 1670s, "love letter," French, literally "sweet note," from billet "document, note" (14c., diminutive of bille; see bill (n.1)) + doux "sweet," from Latin dulcis (see dulcet).
billfold (n.): 1879, from bill (n.1) + fold, here perhaps short for folder.
billiard: singular of billiards, used only in combinations.
billiards (n.): 1590s, from French billiard, originally the word for the wooden cue stick, a diminutive from Old French bille "stick of wood," from Medieval Latin billia "tree, trunk," possibly from Gaulish (compare Irish bile "tree trunk").