bikini (n.)
"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," also the figurative sense of bombshell).
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, "having or appearing to have two lips;" see bi- "two" + labial. In linguistics, of consonants pronounced with both lips, 1878. Alternative bilabiate is attested from 1794.
bilateral (adj.)
"having two sides," 1775; see bi- "two" + lateral (adj.). Related: Bilaterally.
bilateralism (n.)
"state or quality of being bilateral," 1852, from bilateral + -ism.
bilbo (n.)
kind of sword esteemed for temper and elasticity, 1590s, from Bilbao (in English Bilboa), town in northern Spain where swords were made. 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 (n.)). A novel set in the formative years, or the time of spiritual education, of the main character.
bile (n.)
"yellow bitter liquid secreted by the liver that aids in digestion," 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 "bitterness of feeling, peevishness," supposedly caused by excess of bile (especially as black bile, 1797). The Latin word is of uncertain origin.

De Vaan notes apparent cognates in British Celtic (Welsh bustl, Middle Cornish bystel, Breton bestl "gall, bile") and writes, "since this word is only found in Italic and Celtic, it is possible that the word is not PIE." But, he adds, if it was borrowed from Celtic into Italic it might be from PIE root *bheid- "to split," which in Germanic has come to meaning "bite," and notes that "'bile' is a biting substance."
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 bulge (n.) and compare budget (n.)).
biliary (adj.)
"pertaining to bile," 1731, from French biliaire, from bile "bile; peevishness" (see bile). Meaning "bilious in mood or temperament" is recorded from 1837.
bilinear (adj.)
also bi-linear, "of or having reference to two lines," 1847, from Modern Latin (in botany); see bi- "two" + linear. Related: Bilinearly; bilinearity.
bilingual (adj.)
1818, "speaking two languages;" 1825, "expressed in two languages;" see bi- "two" + lingual. Latin bilinguis meant literally "two-tongued," and, figuratively, "speaking a jumble of languages," also "double-tongued, hypocritical, false."
bilingualism (n.)
1854, from bilingual + -ism.
bilious (adj.)
1540s, "pertaining to bile, biliary," from French bilieux, from Latin biliosus "pertaining to bile," from bilis "bile; peevishness" (see bile). Meaning "testy, 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," 1868, from German bilirubin (1864), from bili- "bile" (see bile) + Latin ruber "red" (from PIE root *reudh- "red, ruddy") + -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;" some sources suggest it is a thinned form of balk "to hinder." Meaning "to defraud" is first recorded 1670s. Related: Bilked; bilking.
bill (v.2)
"to stroke beaks," as doves do, hence, of lovers, "caress fondly," 1590s, from bill (n.2)). Paired with coo since at least 1764; Century Dictionary [1902] defines bill and coo (by 1768) as "to kiss and caress and talk nonsense, as lovers." Related: Billed; billing.
bill (n.1)
"written statement," late 14c., "formal document; formal plea or charge (in a court of law); personal letter," from Anglo-French bille, Anglo-Latin billa "a writing, a list, a seal," 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 "written statement detailing articles sold or services rendered by one person to another" is from c. 1400; that of "order addressed to one person to pay another" is from 1570s. Meaning "paper intended to give public notice of something, exhibited in a public place" is from late 15c. Sense of "paper money, bank-note" is from 1660s. Meaning "draft of a proposed statute presented to a legislature" is from 1510s.
bill (n.3)
ancient weapon, Old English bill "sword (especially one with a hooked blade), chopping tool," from Proto-Germanic *bili-, a word for cutting or chopping weapons (compare Old Saxon bil "sword," Middle Dutch bile, Dutch bijl, Old High German bihal, German Beil, Old Norse bilda "hatchet"), possibly 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").
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 Proto-Germanic *bili-, a word for cutting or chopping weapons (see bill (n.3)). Used also in Middle English of beak-like projections of land (such as Portland Bill).
bill (v.1)
"to send someone a bill of charge," 1864, from bill (n.1). Related: Billed; billing.
billable (adj.)
1570s, from bill (v.) + -able.
billabong (n.)
Australian, "backwater, stagnant pool," 1865, from Billibang, Aboriginal name of Bell River, from billa "water" + bang, which is of uncertain meaning.
billboard (n.)
also bill-board, "any sort of board where bills were meant to be posted," 1845, American English, from bill (n.1) "written public notice" + board (n.1). Billboard magazine founded 1894, originally a trade paper for the bill-posting industry; its music sales charts date from the 1930s.
billet (v.)
1590s, "to assign quarters to, to direct (a soldier) by note to a lodging place," from a noun meaning "a ticket given by a military officer directing a person to whom it is addressed to provide board and lodging for the soldier carrying it" (1640s). This was a specific use of the word, which earlier meant merely "official record or register" (late 13c.), from Anglo-French billette "list, schedule," diminutive of bille "written statement" (see bill (n.1)) with -let. From 1830 in the sense "place where a soldier is lodged." Related: Billeted; billeting.
billet (n.2)
"small paper, short document, note," mid-15c., earlier "an official register, roll, or record" (late 13c.), from Anglo-French billette "list, schedule," diminutive of bille "written statement" (see bill (n.1)) with -let.
billet (n.1)
"short, thick stick of wood used for fuel," mid-15c., from Middle French billette, diminutive of bille "stick of wood," from Medieval Latin billia "tree, trunk," which is possibly from Gaulish (compare Irish bile "tree trunk").
billet-doux (n.)
also billet doux, 1670s, "short love letter," French, literally "sweet note," from billet "document, note" (14c., diminutive of bille "a writing, a list, a seal;" see bill (n.1)) + doux "sweet," from Latin dulcis (see dulcet).
billfold (n.)
1879, from bill (n.1) + fold, here perhaps short for folder.
singular of billiards, used only in combinations (such as billiard-ball, 1630s, billiard-table 1640s).
billiards (n.)
game played on as rectangular table with ivory balls and wooden sticks, 1590s, from French billiard, originally the word for the wooden cue stick, a diminutive of Old French bille "stick of wood," from Medieval Latin billia "tree, trunk," which is possibly from Gaulish (compare Irish bile "tree trunk").
billing (n.1)
1875, "announcement on a bill or poster," verbal noun from bill (v.) "post as a public notice" (see bill (n.1)); hence top billing (1928). Meaning "act of sending out a bill" is recorded from 1908.
billing (n.2)
"a dove-like caressing, love-making," 1580s; see bill (v.2).
billingsgate (n.)
1670s, coarse, abusive language of the sort once used by women in the Billingsgate market on the River Thames below London Bridge.
Billingsgate is the market where the fishwomen assemble to purchase fish; and where, in their dealings and disputes they are somewhat apt to leave decency and good manners a little on the left hand. [Grose, "A Classical Dictionary of the Vulgar Tongue," 1788]
The place name is Old English Billingesgate, "gate of (a man called) Billing;" the "gate" probably being a gap in the Roman river wall. The market is from mid-13c.; it was not exclusively a fish market until late 17c.
billion (n.)
1680s, from French billion (originally byllion in Chuquet's unpublished "Le Triparty en la Science des Nombres," 1484; copied by De la Roche, 1520); see bi- "two" + million. A million million in Britain and Germany (numeration by groups of sixes), which was the original sense; subsequently altered in French to "a thousand million" (numeration by groups of threes) and picked up in that form in U.S., "due in part to French influence after the Revolutionary War" [David E. Smith, "History of Mathematics," 1925]. France reverted to the original meaning in 1948. British usage is truer to the etymology, but U.S. sense is said to be increasingly common there in technical writing.
In Italian arithmetics from the last quarter of the fifteenth century the words bilione or duilione, trilione, quadrilione or quattrilione, quintilione, cinquilione, or quinquilione, sestione or sestilione, settilione, ottilione, noeilione and decilione occur as common abbreviations of due volte millioni, tre volte millione, etc. In other countries these words came into use much later, although one French writer, Nicolas Chuquet, mentions them as early as 1484, in a book not printed until 1881. The Italians had, besides, another system of numeration, proceeding by powers of a thousand. The French, who like other northern peoples, took most if not all their knowledge of modern or Arabic arithmetic from the Italians, early confounded the two systems of Italian numeration, counting in powers of a thousand, but adopting the names which properly belong to powers of a million. [Century Dictionary]
For a time in Britain gillion (1961), based on giga-, was tried as "a thousand million" to avoid ambiguity. Compare milliard.
billionaire (n.)
1844, American English, from billion on model of millionaire. Marked [Rare.] in Century Dictionary (1902). The first in the U.S. likely was John D. Rockefeller (1839-1937), some time after World War I.
billionth (adj., n.)
1778, from billion + -th (2).
billow (n.)
"a great wave or surge of the sea," 1550s, perhaps older in dialectal use (but not recorded in Middle English), from Old Norse bylgja "a wave, a billow," from Proto-Germanic *bulgjan (source also of Swedish bölja, Danish bölge "a billow," Middle High German bulge "a billow; a bag"), from PIE *bhelgh- "to swell," extended form of root *bhel- (2) "to blow, swell."
billow (v.)
"to rise or roll in large waves," 1590s, from billow (n.). Related: Billowed; billowing.
billowy (adj.)
1610s, from billow (n.) + -y (2). Related: Billowiness.
billy (n.)
"club," 1848, American English, originally burglars' slang for "crowbar;" meaning "policeman's club" first recorded 1856, probably from nickname of William, applied to various objects (compare jack, jimmy, jenny). But compare French bille "a short, stout stick" (see billet (n.1)). Billy-goat as a familiar name for a male goat is from 1826.
bimbo (n.)
1919, "fellow, chap," from variant of Italian bambino "baby;" first attested in Italian-accented theater dialogue. Originally especially "stupid, inconsequential man, contemptible person;" by 1920 the sense of "floozie" had developed (popularized by "Variety" staffer Jack Conway, d.1928). Resurrection during 1980s U.S. political sex scandals led to derivatives including diminutive bimbette (1990) and male form himbo (1988).
bimetallic (adj.)
also bi-metallic, "composed of two metals," 1864; see bi- "two" + metallic. In economics, "pertaining to the use of both silver and gold as standards in currency," 1876, from French bimétalique (Cornuschi).
bimodal (adj.)
also bi-modal, 1891; see bi- "two" + modal. Related: Bimodality.
bimonthly (adj.)
also bi-monthly, 1846, "happening once in two months, every two months," also "occurring twice a month," a hybrid from bi- "two" + monthly. Bimensal in the same sense is attested in 1670s.
bin (n.)
"enclosed receptacle for some commodity," Old English binne "basket, manger, crib," a word of uncertain origin. Probably from Gaulish, from Old Celtic *benna, and akin to Welsh benn "a cart," especially one with a woven wicker body. The same Celtic word seems to be preserved in Italian benna "dung cart," French benne "grape-gatherer's creel," Dutch benne "large basket," all of which are from Late Latin benna "cart," Medieval Latin benna "basket." Some linguists think there was a Germanic form parallel to the Celtic one.
binary (adj.)
"dual, twofold, double," mid-15c., from Late Latin binarius "consisting of two," from bini "twofold, two apiece, two-by-two" (used especially of matched things), from bis "double" (from PIE root *dwo- "two"). Binary code in computer terminology was in use by 1952, though the idea itself is ancient. Binary star in astronomy is from 1802.
binate (adj.)
"double, growing in pairs," 1807, from Latin bini "two by two, twofold, two apiece" (see binary) + -ate (2). Used especially in botany.
binaural (adj.)
"pertaining to both ears," 1857, from Latin bini "twofold, two apiece" (see binary) + aural. In reference to sound reproduction from electronic recordings, 1933.
bind (n.)
"anything that binds," in various senses, late Old English, from bind (v.). Meaning "tight or awkward situation" is from 1851.
bind (v.)
Old English bindan "to tie up with bonds" (literally and figuratively), also "to make captive; to cover with dressings and bandages" (class III strong verb; past tense band, past participle bunden), from Proto-Germanic *bindan (source also of Old Saxon bindan, Old Norse and Old Frisian binda, Old High German binten "to bind," German binden, Gothic bindan), from PIE root *bhendh- "to bind." Of books, from c. 1400. Intransitive sense of "stick together, cohere" is from 1670s.