The Collaborative International Dictionary of English v.0.48:

Pickaninny \Pick"a*nin`ny\ (p[i^]k"[.a]*n[i^]n`n[y^]), n.; pl.
   Pickaninnies (p[i^]k"[.a]*n[i^]n`n[i^]z). [Cf. Sp.
   peque[~n]o little, young.]
   A small child; especially, a negro or mulatto infant. Now
   (2001) used primarily in the latter sense, and in that sense
   often considered derogatory. [U.S. & West Indies]
   [1913 Webster]