nigger (n.) Look up nigger at Dictionary.com
1786, earlier neger (1568, Scottish and northern England dialect), 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 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.
"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]
Also applied by English settlers to dark-skinned native peoples in India, Australia, Polynesia. 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.

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. Variant niggah, attested from 1925 (without the -h, from 1969), is found usually in situations where blacks use the word. Nigra (1944), on the other hand, in certain uses reflects a pronunciation of negro meant to suggest nigger, and is thus deemed (according to a 1960 slang dictionary) "even more derog[atory] than 'nigger.' " Slang phrase nigger in the woodpile attested by 1800; "A mode of accounting for the disappearance of fuel; an unsolved mystery" [R.H. Thornton, "American Glossary," 1912]. Nigger heaven "the top gallery in a (segregated) theater" first attested 1878 in reference to Troy, N.Y.