denigrate v.

active word-forming element in English and in many verbs inherited from French and Latin, from Latin de "down, down from, from, off; concerning" (see de), also used as a prefix in Latin, usually meaning "down, off, away, from among, down from," but also "down to the bottom, totally" hence "completely" (intensive or completive), which is its sense in many English words.

As a Latin prefix it also had the function of undoing or reversing a verb's action, and hence it came to be used as a pure privative — "not, do the opposite of, undo" — which is its primary function as a living prefix in English, as in defrost (1895), defuse (1943), de-escalate (1964), etc. In some cases, a reduced form of dis-.

1550s, "member of a black-skinned race of Africa," from Spanish or Portuguese negro "black," from Latin nigrum (nominative niger) "black, dark, sable, dusky" (applied to the night sky, a storm, the complexion), figuratively "gloomy, unlucky, bad, wicked," according to de Vaan a word of unknown etymology; according to Watkins, perhaps from PIE *nekw-t- "night." The Latin word also was applied to the black peoples of Africa, but the usual terms were Aethiops and Afer.

As an adjective from 1590s. Use with a capital N- became general early 20c. (e.g. 1930 in "New York Times" stylebook) in reference to U.S. citizens of African descent, but because of its perceived association with white-imposed attitudes and roles the word was ousted late 1960s in this sense by Black (q.v.).

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 "African-American vernacular, the English language as spoken by U.S. blacks" is from 1704. French nègre is a 16c. borrowing from Spanish negro. Older English words were Moor and blackamoor. A Middle English word for "Ethiopian" (perhaps also "a negro" generally) was blewman "blue man."