The Collaborative International Dictionary of English v.0.48:

Capon \Ca"pon\, v. t.
   To castrate; to make a capon of.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Capon \Ca"pon\ (k[=a]"p'n or k[=a]"p[u^]n; 277), n. [OE. capon,
   chapoun, AS. cap[=u]n (cf. F. chapon), L. capo, fr. Gr.
   ka`pwn akin to ko`ptein to cut, OSlav. skopiti to castrate.
   Cf. Comma.]
   A castrated cock, esp. when fattened; a male chicken gelded
   to improve his flesh for the table. --Shak.
   [1913 Webster]

         The merry thought of a capon.            --W. Irving.
   [1913 Webster]

WordNet (r) 3.0 (2006):

capon
    n 1: flesh of a castrated male chicken
    2: castrated male chicken