bittern (n.)
heron-like bird, 13c., botor, from Old French butor "bittern," perhaps from Gallo-Roman *butitaurus, from Latin butionem "bittern" + taurus "bull" (see steer (n.)); according to Pliny, so called because of its booming voice, but this seems fanciful. Modern form from 1510s.
bitterness (n.)
Old English biternys "bitterness, grief;" see bitter + -ness. Figurative sense (of feelings, etc.) is attested earlier than literal sense (of taste), which will surprise no one who reads any amount of Anglo-Saxon literature.
bitters (n.)
1713, from bitter. So called for its taste.
bittersweet
also bitter-sweet, late 14c. as a noun; used especially in Middle English of a type of apple, from bitter (adj.) + sweet (adj.). As an adjective, attested from 1610s.
BitTorrent
peer-to-peer file sharing protocol, implemented in 2001, from bit (n.2) in the computing sense + torrent.
bitty (adj.)
1892, "made of little scraps," from bit (n.1) + -y (2). As a clipped variant of bitsy, recorded from 1905, American English.
bitumen (n.)
mid-15c., from Latin bitumen "asphalt," probably, via Oscan or Umbrian, from Celtic *betu- "birch, birch resin" (compare Gaulish betulla "birch," used by Pliny for the tree supposedly the source of bitumen).
bituminous (adj.)
1610s, from French bitumineux, from Latin bituminosus, from bitumen (see bitumen).
The Plain, wherein a black bituminous gurge Boiles out from under ground, the mouth of Hell. ["Paradise Lost," XII.41]
bivalence (n.)
1868; see bivalent + -ence.
bivalency (n.)
1872; see bivalent + -ency.
bivalent (adj.)
1864, of chemicals, 1899, of chromosomes, from bi- + -valent, from Latin valentem, present participle of valere "be worth" (see valiant).
bivalve (adj.)
1660s in reference to mollusks with double shells; 1670s in reference to shutters or doors; from bi- + valve. The noun is 1680s in the mollusk sense.
bivariate (adj.)
also bi-variate, "involving two variables," 1906, from bi- + -variate, from Latin variatio (see variation).
bivouac (n.)
1702, from French bivouac (17c.), ultimately from Swiss/Alsatian biwacht "night guard," from bei- "double, additional" + wacht "guard" (see wait (v.)). Original meaning was an army that stayed up on night watch; sense of "outdoor camp" is 1853. Not a common word in English before the Napoleonic Wars. Italian bivacco is from French. As a verb, 1809, "to post troops in the night;" meaning "camp out of doors" is from 1814.
biweekly (adj.)
also bi-weekly, 1865, from bi- + weekly. The sense "twice a week" is the first attested, but that of "every two weeks" is equally implied.
biz (n.)
1862, American English, colloquial and phonetic shortening of business.
bizarre (adj.)
1640s, from French bizarre "odd, fantastic" (16c.), originally "handsome, brave," perhaps from Basque bizar "a beard" (the notion being of bearded Spanish soldiers making a strange impression on the French); alternative etymology traces it to Italian bizarro "angry, fierce, irascible," from bizza "fit of anger."
bize
obsolete form of bice.
blab (v.)
mid-15c., apparently from Middle English noun blabbe "one who does not control his tongue" (late 13c.), probably echoic. Related: Blabbed; blabbing. The exact relationship between the blabs and blabber is difficult to determine. The noun was "[e]xceedingly common in 16th and 17th c.; unusual in literature since c 1750" [OED].
blabber (v.)
mid-14c., "to speak as an infant speaks," frequentative of blabben, of echoic origin (compare Old Norse blabbra, Danish blabbre "babble," German plappern "to babble"). Meaning "to talk excessively" is from late 14c. Related: Blabbered; blabbering.
blabbermouth (n.)
1931, from blabber + mouth (n.).
black (adj.)
Old English blæc "dark," from Proto-Germanic *blakaz "burned" (cognates: Old Norse blakkr "dark," Old High German blah "black," Swedish bläck "ink," Dutch blaken "to burn"), from PIE *bhleg- "to burn, gleam, shine, flash" (cognates: Greek phlegein "to burn, scorch," Latin flagrare "to blaze, glow, burn"), from root *bhel- (1) "to shine, flash, burn;" see bleach (v.).

The same root produced Old English blac "bright, shining, glittering, pale;" the connecting notions being, perhaps, "fire" (bright) and "burned" (dark). The usual Old English word for "black" was sweart (see swart). According to OED: "In ME. it is often doubtful whether blac, blak, blake, means 'black, dark,' or 'pale, colourless, wan, livid.' " Used of dark-skinned people in Old English.

Of coffee, first attested 1796. Meaning "fierce, terrible, wicked" is late 14c. The color of sin and sorrow since at least c.1300; sense of "with dark purposes, malignant" emerged 1580s (as in black magic). Black face in reference to a performance style originated in U.S., is from 1868. Black flag, flown (especially by pirates) as a signal of "no mercy," from 1590s. Black dog "melancholy" attested from 1826. Black belt is from 1875 in reference to districts of the U.S. South with heaviest African population; 1870 with reference to fertility of soil; 1913 in judo sense. Black power is from 1966, associated with Stokely Carmichael.
black (v.)
c.1200, "to become black;" early 14c., "to make black, darken;" from black (adj.). Related: Blacked; blacking.
black (n.)
Old English blæc "the color black," also "ink," from noun use of black (adj.). From late 14c. as "dark spot in the pupil of the eye." The meaning "black person, African" is from 1620s (perhaps late 13c., and blackamoor is from 1540s). To be in the black (1922) is from the accounting practice of recording credits and balances in black ink.
For years it has been a common practice to use red ink instead of black in showing a loss or deficit on corporate books, but not until the heavy losses of 1921 did the contrast in colors come to have a widely understood meaning. ["Saturday Evening Post," July 22, 1922]
black box (n.)
1947, RAF slang for "navigational instruments;" later extended to any sort of apparatus that operates in a sealed container. Especially of flight recorders from c.1964.
black code (n.)
local or state legal restrictions on black persons, free or slave; attested by 1840, American English, though the thing itself is much older.
black comedy (n.)
first recorded 1961, from black (adj.) in a figurative sense of "morbid;" compare French pièce noire. In a racial sense, from 1921.
Black Death (n.)
"bubonic/pneumonic plague epidemic of 1347-51 in Europe," a modern name, introduced in English 1823 by Elizabeth Penrose's history of England. The contemporary name for it in most languages was something like "the great dying" or simply "the plague" (or, looking back after its return, "the first pestilence"). The term "Black Death" first turns up in 16c. Swedish and Danish chronicles, but in reference to a visitation of plague in Iceland in 1402-3 that carried off much of the population there (which had been spared in the earlier outbreak). The exact sense of "black" is not clear. The term appears in English translations of the Scandinavian works from 1750s. It was picked up in German c.1770 and applied to the earlier outbreak, and taken from there into English in that sense.
black dwarf (n.)
in astrophysics, a kind of dead and lightless star, 1966.
Black English (n.)
English as spoken by African-Americans, by 1969.
black eye (n.)
"discoloration around the eye from injury" c.1600, from black (adj.) + eye (n.). Figurative sense of "injury to pride, rebuff" is by 1744; that of "bad reputation" is from 1880s. In reference to dark eyes, often as a mark of beauty, from 1660s. Black-eyed, of peas, attested from 1728. The black-eyed Susan as a flower (various species) so called from 1881, for its appearance. It also was the title of a poem by John Gay (1685-1732), which led to a popular British stage play of the same name in the mid-19c.
All in the Downs the fleet was moored,
The streamers waving in the wind,
When black-eyed Susan came aboard,
"Oh! where shall I my true love find?
Tell me, ye jovial sailors, tell me true,
If my sweet William sails among the crew?"
black friar (n.)
"Dominican," c.1500, so called from the color of their dress.
Black Hand (n.)
Italian immigrant secret society in U.S., 1904; earlier a Spanish anarchist society, both from the warning mark they displayed to potential victims.
Black Hills
South Dakota landform, translating Lakhota pahá-sapa; supposedly so called because their densely forested flanks look dark from a distance.
black hole (n.)
in astrophysics, 1968, probably with awareness of Black Hole of Calcutta, incident of June 19, 1756, in which 146 British POWs taken by the Nawab of Bengal after the capture of Ft. William, Calcutta, were held overnight in punishment cell of the barracks (meant to hold 4 people) and all but 23 perished.
black letter
early 17c., from black (adj.); so called to distinguish heavy, old-style printers' types from the ones coming into use then, which are the dominant modern forms, though a style of black letter was preserved in German into 20c.
black market (n.)
1931, from black + market.
Black Panther
1965, the movement an outgrowth of Student Nonviolent Co-ordinating Committee.
Black Sea
see Euxine.
black sheep (n.)
by 1822 in figurative sense of "member of some group guilty of offensive conduct and unlike the other members," supposedly because a real black sheep had wool that could not be dyed and was thus worth less. But one black sheep in a flock was considered good luck by shepherds in Sussex, Somerset, Kent, Derbyshire. Baa Baa Black Sheep nursery rhyme's first known publication is in "Tommy Thumb's Pretty Song Book" (c.1744).
Black Shirt
1922, member of Fasci di Combattimento, Italian paramilitary unit founded 1919 by Mussolini; so called for their uniforms.
black widow (n.)
type of poisonous spider (Latrodectus mactans) in U.S. South, 1904, so called from its color and from the female's supposed habit of eating the male after mating (they are cannibalistic, but this particular behavior is rare in the wild). Sometimes also known as shoe-button spider. The name black widow is attested earlier (1830s) as a translation of a name of the "scorpion spider" of Central Asia.
Blackamoor (n.)
"dark-skinned person," 1540s, from black (adj.) + Moor, with connecting element.
blackball (v.)
also black-ball, "to exclude from a club by adverse votes," 1770, from black (adj.) + ball (n.1). Black balls of wood or ivory dropped into an urn during secret ballots.
blackberry (n.)
early 12c., from Old English blaceberian, from black (adj.) + berry. Also in Old English as bremelberie, bremelæppel (from bramble). The wireless handheld device of the same name introduced 1999.
blackbird (n.)
late 15c. (late 13c. as a surname), from black (adj.) + bird (n.1). OED says so called for being the only "black" (really dark brown) bird among the songbirds, reflecting an older sense of bird that did not include rooks, crows, ravens.
blackboard (n.)
1823, from black + board (n.1). Blackboard jungle "inner-city school rife with juvenile delinquency" is from Evan Hunter's novel title (1954).
blacken (v.)
c.1200, "become black or dark;" early 14c., "make black, darken, dye (hair);" see black + -en (1). Figurative sense of "to besmirch" (with dishonor, etc.) is from early 15c. Related: Blackened; blackening.
blackguard (n.)
1530s, scullion, kitchen knave. Perhaps once an actual military or guard unit; more likely originally a mock-military reference to scullions and kitchen-knaves of noble households, of black-liveried personal guards, and of shoeblacks. By 1736, sense had emerged of "one of the criminal class." Hence the adjectival use (1784), "of low or worthless character."
blackhead (n.)
"comedo," 1837, from black (adj.) + head (n.). So called for its appearance.