1. prevent the growth of horns of certain animals
2. take the horns off (an animal)
The Collaborative International Dictionary of English v.0.48:
Dehorn \De*horn"\, v. t. [imp. & p. p. Dehorned; p. pr. & vb.
To deprive of horns; to prevent the growth of the horns of
(cattle) by burning their ends soon after they start. See
Dishorn. "Dehorning cattle." --Farm Journal (1886).
WordNet (r) 3.0 (2006):
v 1: prevent the growth of horns of certain animals
2: take the horns off (an animal)