biennial (adj.) Look up biennial at Dictionary.com
1629s, "lasting for two years;" 1750, "occurring every two years," from Latin biennium "two-year period," from bi- "two" (see bi-) + annus "year" (see annual (adj.)). The vowel change is "due to the Latin phonetic law according to which the unaccented and closed radical syllable of the second element of compounds, original -ă- becomes -ĕ-" [Klein]. The noun meaning "a biennial plant" (which requires two seasons of growth to produce flowers and fruit and dies the next) is attested by 1770. Related: Biennially.
biennium (n.) Look up biennium at Dictionary.com
"space of two years," 1835, from Latin biennium "two years, a period of two years," from bi- "two" (see bi-) + annus "year" (see annual (adj.)). For vowel change, see biennial.
bier (n.) Look up bier at Dictionary.com
Old English bær (West Saxon), ber (Anglian) "handbarrow, litter, bed," from West Germanic *bero (source also of Old Saxon, Old High German bara, Old Frisian bere, Middle Dutch bare, Dutch baar, German Bahre "bier"), from PIE root *bher- (1) "to carry."

The original sense is "wooden frame on which to carry a load," and it is related to bear (v.). Specific sense of "framework on which a coffin or corpse is laid before burial" was in late Old English and predominated from c. 1600. The spelling altered from c. 1600 under influence of French bière, from Old French biere, from Frankish *bera, from the same Germanic source.
bifarious (adj.) Look up bifarious at Dictionary.com
"divided in two parts," 1650s, from Latin bifarius "twofold, double," probably originally "that which can be expressed in two ways" [Klein], from bi- "two" (see bi-) + fari "to speak, say" (from PIE root *bha- (2) "to speak, tell, say"). Related: Bifariously.
biff (v.) Look up biff at Dictionary.com
"to hit," 1877, imitative (as a sound effect by 1847). Related: Biffed; biffing. As a noun, attested from 1881.
bifid (adj.) Look up bifid at Dictionary.com
"cleft, forked, split halfway down into two equal parts," 1660s, from Latin bifidus "split into two parts," from bi- "two" (see bi-) + -fid, from stem of findere "to split" (from PIE root *bheid- "to split"). Related: Bifidity.
bifocal (adj.) Look up bifocal at Dictionary.com
"having two foci," 1844; see bi- "two" + focal.
bifocals (n.) Look up bifocals at Dictionary.com
"bifocal spectacles," 1883, bi-focals; see bifocal. Invented by Benjamin Franklin, but he called them double spectacles.
bifold (adj.) Look up bifold at Dictionary.com
"double, of two kinds," c. 1600; see bi- "two" + -fold.
bifoliate (adj.) Look up bifoliate at Dictionary.com
"having two leaves or leaflets," 1817; see bi- "two" + foliate.
bifurcate (v.) Look up bifurcate at Dictionary.com
"to divide into two forks or branches," 1610s, from Medieval Latin bifurcatus, from Latin bi- "two" (see bi-) + furca "two-pronged fork, fork-shaped instrument," a word of unknown etymology. Related: Bifurcated; bifurcating.
bifurcate (adj.) Look up bifurcate at Dictionary.com
"two-forked," 1835, from Medieval Latin bifurcatus, from Latin bi- "two" (see bi-) + furca "two-pronged fork," a word of unknown etymology. Nativized biforked in the same sense is from 1570s.
bifurcation (n.) Look up bifurcation at Dictionary.com
1610s, "the point at which something splits in two," noun of action from bifurcate (v.). Meaning "a division into two forks" is from 1640s.
big (adj.) Look up big at Dictionary.com
c. 1300, at first found chiefly in northern England and north Midlands writing, "powerful, strong," of obscure origin, possibly from a Scandinavian source (compare Norwegian dialectal bugge "great man"). Old English used micel (see much) in many of the same senses. It came into general use c. 1400. Meaning "of great size" is late 14c.; that of "full-grown, grown up" is attested from late 14c. Sense of "important, influential, powerful" is from c. 1400. Meaning "haughty, inflated with pride" is from 1570s. Meaning "generous" is U.S. colloquial by 1913.

Big band as a musical style is from 1926. Slang big head "conceit" is first recorded 1850. Big business "large commercial firms collectively" is from 1913 (before that it meant "a profitable income in business"). Big top "main tent of a circus" is from 1895. Big game "large animals hunted for sport" is from 1864. big house "penitentiary" is U.S. underworld slang first attested 1915 (in London, "a workhouse," 1851). In financial journalism, big ticket items so called from 1956. Big lie is from Hitler's grosse Lüge.
Big Apple (n.) Look up Big Apple at Dictionary.com
"New York City," 1909 (but popularized by 1970s tourism promotion campaign), apparently from jazz musicians' use of apple for any city, especially a Northern one.
big bang (n.) Look up big bang at Dictionary.com
hypothetical explosive beginning of the universe, developed from the work of astronomers Monsignor Georges Henri Joseph Édouard Lemaître and George Gamow; the phrase is first attested 1950 (said to have been used orally in 1949) by British astronomer Fred Hoyle (1915-2001) in an attempt to explain the idea in laymen's terms.
Big Ben (n.) Look up Big Ben at Dictionary.com
clock-bell in the Parliament tower in London, by 1861, generally said to have been named for Sir Benjamin Hall (1802-1867), first Chief Commissioner of Works, under whose supervision the bell was cast. The name later was extended to the clock itself and its tower.
Big Brother (n.) Look up Big Brother at Dictionary.com
"ubiquitous and repressive but apparently benevolent authority" first recorded 1949, from George Orwell's novel "Nineteen Eighty-Four." The phrase big brother for "older brother" is attested by 1833.
big deal (n.) Look up big deal at Dictionary.com
from 1860s as "a good deal, a large amount;" by 1878 in financial speculation, originally in California publications; see deal (n.1). As an ironic expression, popular in American English from c. 1965, perhaps a translated Yiddishism (such as a groyser kunst).
Big Dipper (n.) Look up Big Dipper at Dictionary.com
American English name for the seven-star asterism (known in England as the plough; see Charles's Wain) in the constellation Ursa Major, 1845; attested 1833 as simply the Dipper (sometimes Great Dipper, its companion constellation always being the Little Dipper). See dipper.
Big Mac Look up Big Mac at Dictionary.com
trademark name (McDonald's Corp.) of a type of large hamburger sandwich; by 1968.
big shot (n.) Look up big shot at Dictionary.com
"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; see shot (n.).
big time (n.) Look up big time at Dictionary.com
"upper reaches of a profession or pursuit," by 1909 in vaudeville slang. As an adjective by 1915. The same phrase was common in colloquial use late 19c.-early 20c. in a broad range of senses: "party, shindig, fun, frolic."
big-boned (adj.) Look up big-boned at Dictionary.com
"stout," 1580s, now often considered euphemistic.
big-league (adj.) Look up big-league at Dictionary.com
"prominent, important, first-rate," by 1925, a figurative use from baseball, where big league was used for "a major league" by 1891. See league (n.1).
big-mouth (n.) Look up big-mouth at Dictionary.com
also bigmouth "person who talks too much," 1889, American English, from big + mouth (n.). Earlier as a type of fish and the name of a capable leader of the Oglala people in the 1860s.
big-tent (adj.) Look up big-tent at Dictionary.com
in reference to welcoming all sorts and not being ideologically or theologically narrow, American English, 1982 with reference to religion, by 1987 with reference to politics.
bigamist (n.) Look up bigamist at Dictionary.com
"one who has had two or more wives or husbands at once," 1630s; see bigamy + -ist. Earlier in the same sense was bigame (mid-15c.), from Old French bigame, from Medival Latin bigamus.
bigamous (adj.) Look up bigamous at Dictionary.com
"pertaining to or guilty of bigamy," 1690s; see bigamy + -ous.
bigamy (n.) Look up bigamy at Dictionary.com
"state of having two wives or husbands at the same time," mid-13c., from Old French bigamie (13c.), from Medieval Latin bigamia "bigamy," from Late Latin bigamus "twice married," a hybrid from bi- "double" (see bi-) + Greek gamos "marrying" (see gamete). The Greek word was digamia, from 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.) Look up bigass at Dictionary.com
also big-ass, big-assed, by 1945, U.S. military slang, from big + ass (2).
bigfoot (n.) Look up bigfoot at Dictionary.com
supposed elusive man-like creature of the Pacific Northwest, 1963, from big (adj.) + foot (n.).
biggen (v.) Look up biggen at Dictionary.com
1640s, "to make big, increase," also "grow big, become larger," from big (adj.) + -en (1). As a noun, bigger is attested from mid-15c. for "builder."
bigger (adj.) Look up bigger at Dictionary.com
comparative of big (q.v.).
biggest (adj.) Look up biggest at Dictionary.com
superlative of big (q.v.).
biggie (n.) Look up biggie at Dictionary.com
1931, "important person," from big + -ie.
bighorn (n.) Look up bighorn at Dictionary.com
"Rocky Mountain sheep," 1805, American English, from big + horn (n.).
bight (n.) Look up bight at Dictionary.com
Old English byht "bend, angle, corner," from Proto-Germanic *buhtiz (source also of Middle Low German bucht, German Bucht, Dutch bocht, Danish bught "bight, bay"), from PIE root *bheug- "to bend," with derivatives referring to bent, pliable, or curved objects. Sense of "long, narrow indentation on a coastline" is from late 15c.
bigly (adv.) Look up bigly at Dictionary.com
early 14c., "strongly, vehemently," from big + -ly (2). From 1530s as "haughtily, arrogantly."
bigness (n.) Look up bigness at Dictionary.com
late 15c., from big + -ness.
bigot (n.) Look up bigot at Dictionary.com
1590s, "sanctimonious person, religious hypocrite," from French bigot (12c.), which is of unknown origin. Sense extended 1680s to other than religious opinions.

Earliest French use of the word is as the name of a people apparently in southern Gaul, which led to the theory, now considered doubtful on phonetic grounds, that the word comes from Visigothus. The typical use in Old French seems to have been as a derogatory nickname for Normans, leading to another theory (not universally accepted) that traces it to the Normans' (alleged) frequent use of the Germanic oath bi God. 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 as the origin of the word, but not explained, so the chief virtue of that theory is the lack of evidence for or against it.

In support of the "by God" theory the surnames 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 son of a bitch) for their characteristic oaths. But the sense development in bigot would be difficult to explain. According to Donkin, the modern use first appears in French in 16c. This and the earliest English sense, "religious hypocrite," especially a female one, might have been influenced by or confused with beguine (q.v.) and the words that cluster around it.
bigoted (adj.) Look up bigoted at Dictionary.com
"obstinately and blindly devoted to a particular creed, opinion, etc.," 1640s, from bigot (q.v.).
bigotry (n.) Look up bigotry at Dictionary.com
"obstinate and unreasonable attachment to a creed or opinion and intolerance of others," 1670s, from French bigoterie "sanctimoniousness," from bigot (see bigot).
bigwig (n.) Look up bigwig at Dictionary.com
also big-wig, "great man, person of consequence," 1781, from big + wig, in reference to the imposing wigs formerly worn by men of rank or authority.
bijou (n.) Look up bijou at Dictionary.com
"small item of ornamental jewelry," 1660s, from French bijou, which according to OED is probably from Breton bizou "(jeweled) ring," from bez "finger" (compare Cornish bisou "finger-ring," 13c.). Related: Bijouterie.
bike (n.) Look up bike at Dictionary.com
1882, American English, shortened and altered form of bicycle (n.). As a verb by 1895. Related: Biked; biking.
biker (n.) Look up biker at Dictionary.com
"motorcycle rider" (especially with reference to club affiliation), 1968, American English, from bike (n.) in its slang sense of "motorcycle" (1939). An Australian equivalent was bikie.
bikini (n.) Look up bikini at Dictionary.com
"low-waisted two-piece women's bathing suit," 1948, from French, coined 1947, named for the U.S. A-bomb test of June 1946 on Bikini, the 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.) Look up bilabial at Dictionary.com
1857, "having or appearing to have two lips;" see bi- "two" + labial. Of consonants pronounced with the lips, by 1894. Alternative bilabiate is attested from 1794.
bilateral (adj.) Look up bilateral at Dictionary.com
"having two sides," 1775; see bi- "two" + lateral (adj.). Related: Bilaterally.