The Collaborative International Dictionary of English v.0.48:

Negro \Ne"gro\ (n[=e]"gr[-o]), n.; pl. Negroes
   (n[=e]"gr[=o]z). [Sp. or Pg. negro, fr. negro black, L.
   niger; perh. akin to E. night.]
   A black man; especially, one of a race of black or very dark
   persons who inhabit the greater part of tropical Africa, and
   are distinguished by crisped or curly hair, flat noses, and
   thick protruding lips; also, any black person of unmixed
   African blood, wherever found.
   [1913 Webster]

   2. A person of dark skin color descended at least in part
      from African negroes; in the United States, an
      African-American. [U.S. usage, sometimes considered
      offensive.]
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Negro \Ne"gro\, a.
   Of or pertaining to negroes; black.
   [1913 Webster]

   Negro bug (Zool.), a minute black bug common on the
      raspberry and blackberry. It produces a very disagreeable
      flavor.

   negro corn, the Indian millet or durra; -- so called in the
      West Indies. See Durra. --McElrath.

   Negro fly (Zool.), a black dipterous fly (Psila rosae)
      which, in the larval state, is injurious to carrots; --
      called also carrot fly.

   Negro head (Com.), Cavendish tobacco. [Cant] --McElrath.

   Negro monkey (Zool.), the moor monkey.
      [1913 Webster]

WordNet (r) 3.0 (2006):

negro
    adj 1: relating to or characteristic of or being a member of the
           traditional racial division of mankind having brown to
           black pigmentation and tightly curled hair
    n 1: a person with dark skin who comes from Africa (or whose
         ancestors came from Africa) [syn: Black, Black person,
         blackamoor, Negro, Negroid]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "Negro":
   American Indian, Amerind, Australian aborigine, Bushman, Caucasian,
   Indian, Malayan, Mister Charley, Mongolian, Negrillo, Negrito,
   Oriental, Red Indian, WASP, black, black man, blackfellow, boy,
   brown man, burrhead, colored person, coon, darky, gook, honky,
   jigaboo, jungle bunny, nigger, niggra, ofay, paleface, pygmy,
   red man, redskin, slant-eye, spade, the Man, white, white man,
   whitey, yellow man



The Devil's Dictionary (1881-1906):

NEGRO, n.  The _piece de resistance_ in the American political
problem.  Representing him by the letter n, the Republicans begin to
build their equation thus:  "Let n = the white man."  This, however,
appears to give an unsatisfactory solution.