ラテン語のniger(黒い、暗い)が語源で、おそらくPIE*nekw(暗い、夜)が語源であろう。
Professor Booker T. Washington, being politely interrogated ... as to whether negroes ought to be called 'negroes' or 'members of the colored race' has replied that it has long been his own practice to write and speak of members of his race as negroes, and when using the term 'negro' as a race designation to employ the capital 'N' ["Harper's Weekly," June 2, 1906]Meaning "English language as spoken by U.S. blacks" is from 1704. French nègre is a 16c. borrowing from Spanish negro.