The exact color to which the Gmc. term applies varies in the older dialects; M.H.G. bla is also 'yellow,' whereas the Scandinavian words may refer esp. to a deep, swarthy black, e.g. O.N. blamaðr, N.Icel. blamaður 'Negro' [Buck]
Few words enter more largely into the composition of slang, and colloquialisms bordering on slang, than does the word BLUE. Expressive alike of the utmost contempt, as of all that men hold dearest and love best, its manifold combinations, in ever varying shades of meaning, greet the philologist at every turn. [John S. Farmer, "Slang and Its Analogues Past and Present," 1890, p.252]
The color of constancy since Chaucer at least, but apparently for no deeper reason than the rhyme in true blue (c. 1500). From early times blue was the distinctive color of the dress of servants, which may be the reason police uniforms are blue, a tradition Farmer dates to Elizabethan times. For blue ribbon see cordon bleu under cordon. Blue whale attested from 1851, so called for its color. The flower name blue bell is recorded by 1570s. Blue streak, of something resembling a bolt of lightning (for quickness, intensity, etc.) is from 1830, U.S. Western slang.
Whan pyes chatter vpon a house it is a sygne of ryghte euyll tydynges. [1507]
Divination by number of magpies is attested from c. 1780 in Lincolnshire; the rhyme varies from place to place, the only consistency being that one is bad, two are good.second letter of the Latin alphabet, corresponding to Greek beta, Phoenician beth, literally "house." It "has nothing of that variety of pronunciation shown by most English letters" [Century Dictionary]. The Germanic "b" is said to represent a "bh" sound in Proto-Indo-European, which continued as "bh" in Sanskrit, became "ph" in Greek (brother/Greek phrater; bear (v.)/Greek pherein) and "f" in Latin (frater, ferre).
Often indicating "second in order." B-movie is by 1939, usually said to be so called from being the second, or supporting, film in a double feature. Some film industry sources say it was so called for being the second of the two films major studios generally made in a year, and the one cast with less headline talent and released with less promotion. And early usage varies with grade-B movie, suggesting a perceived association with quality.
B-side of a gramophone single is by 1962 (flip-side is by 1949). B-girl, abbreviation of bar girl, U.S. slang for a woman paid to encourage customers at a bar to buy her drinks, is by 1936.