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]

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.