Proto-Indo-European root meaning "to shine, flash, burn," also "shining white" and forming words for bright colors.

It forms all or part of: beluga; Beltane; black; blancmange; blanch; blank; blanket; blaze (n.1) "bright flame, fire;" bleach; bleak; blemish; blench; blende; blend; blind; blindfold; blitzkrieg; blond; blue (adj.1); blush; conflagration; deflagration; effulgence; effulgent; flagrant; flambe; flambeau; flamboyant; flame; flamingo; flammable; Flavian; Flavius; fulgent; fulminate; inflame; inflammable; phlegm; phlegmatic; phlogiston; phlox; purblind; refulgent; riboflavin.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhrajate "shines;" Greek phlegein "to burn;" Latin flamma "flame," fulmen "lightning," fulgere "to shine, flash," flagrare "to burn, blaze, glow;" Old Church Slavonic belu "white;" Lithuanian balnas "pale."

Old English sweart "black, dark," of night, clouds, also figurative, "wicked, infamous," from Proto-Germanic *swarta- (source also of Old Frisian, Old Saxon, and Middle Dutch swart, Dutch zwart, Old Norse svartr, German schwarz, Gothic swarts "dark-colored, black"), from PIE root *swordo- "dirty, dark, black" (source of sordid). The true Germanic word, surviving in the Continental languages but displaced in English by black. Of skin color of persons from late 14c. Related: Swartest.

"dark-skinned person, black-skinned African," 1540s, from black (adj.) + Moor, with connecting element.

1570s, "thing which makes (something else) black;" c. 1600, "action of making black," verbal noun from black (v.).

pigment or ink made with pure, fine carbon, originally from the soot produced by burning oil in lamps, 1590s, see lamp (n.) + black (n.).

1786, earlier neger (1568, Scottish and northern England dialect), negar, negur, from French nègre, from Spanish negro (see Negro). From the earliest usage it was "the term that carries with it all the obloquy and contempt and rejection which whites have inflicted on blacks" [cited in Gowers, 1965, probably Harold R. Isaacs]. But as black African inferiority was at one time a near universal assumption in English-speaking lands, the word in some cases could be used without deliberate insult. More sympathetic writers late 18c. and early 19c. seem to have used black (n.) and, after the American Civil War, colored person.

Nigger is more English in form than negro, and was formerly and to some extent still is used without intent; but its use is now confined to colloquial or illiterate speech, in which it generally conveys more or less of contempt. [Century Dictionary, 1895]

"You're a fool nigger, and the worst day's work Pa ever did was to buy you," said Scarlett slowly. ... There, she thought, I've said "nigger" and Mother wouldn't like that at all. [Margaret Mitchell, "Gone With the Wind," 1936]

It was also applied by English colonists to the dark-skinned native peoples in India, Australia, Polynesia.

One hears the contemptuous term "nigger" still applied to natives by those who should know better, especially by youths just come from home, and somewhat intoxicated by sudden power. [Samuel Smith, "India Revisited," in "The Contemporary Review," July 1886]

 The reclamation of the word as a neutral or positive term in black culture (not universally regarded as a worthwhile enterprise), often with a suggestion of "soul" or "style," is attested first in the U.S. South, later (1968) in the Northern, urban-based Black Power movement. The variant nigga, attested from 1827 (as niggah from 1835), is found usually in situations where blacks use the word. Also compare nigra.

[F]or when a town black has called a country black (equally black with himself) a "dam black plantation nigga," you may know that he has been terribly provoked, and has now ejected his last drop of gall in that most contemptuous epithet. [The Pamphleteer, vol. XXVIII, No. LVI, 1827]

Used in combinations (such as nigger-brown) since 1840s for various dark brown or black hues or objects; euphemistic substitutions (such as Zulu) began to appear in these senses c. 1917. Brazil nuts were called nigger toes by 1896. Nigger stick "prison guard's baton" is attested by 1971. To work like a nigger "work very hard" is by 1836.

Slang phrase nigger in the woodpile "a concealed motive or unknown factor affecting a situation in an adverse way" [OED] is attested by 1800; Thornton's "American Glossary" (1912) defines it as "A mode of accounting for the disappearance of fuel," hence "an unsolved mystery." Nigger heaven "the top gallery in a (segregated) theater" first attested 1878 in reference to Troy, N.Y. Nigger-shooter "slingshot" is by 1876.

1961, "comedy that deals in themes and subjects usually regarded as serious or taboo," from black (adj.), in a figurative sense of "morbid," + comedy. Compare French pièce noire, also comédie noire "macabre or farcical rendering of a violent or tragic theme" (1958, perhaps the inspiration for the English term) and 19th-century gallows-humor. In a racial sense, from 1921.

"discoloration around the eye from injury" c. 1600, from black (adj.) + eye (n.). The 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 is from 1590s in reference to women, from 1728 in reference to peas. The black-eyed Susan as a flower name (various species) is by 1881, for their appearance. It also was the title of a poem by John Gay (1685-1732), which led to a popular mid-19c. British stage play of the same name.

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?"

[etc.]

"unauthorized dealing in restricted or rationed commodities," 1931, from black (adj.), probably suggesting "dark, invisible" or "shady, improper," + market (n.). As an adjective by 1935. Use of the phrase rose when World War II rationing began.

also black-ball, "to exclude from a club by adverse votes," 1770, from black (adj.) + ball (n.1). The image is of the black balls of wood or ivory that were dropped into an urn as adverse votes during secret ballots. Related: Blackballed; blackballing.