The Collaborative International Dictionary of English v.0.48:

Ebonize \Eb"on*ize\, v. t. [imp. & p. p. Ebonized; p. pr. &
   vb. n. Ebonizing.]
   To make black, or stain black, in imitation of ebony; as, to
   ebonize wood.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ebonize
    v 1: stain black to make it look like ebony [syn: ebonize,
         ebonise]