The Collaborative International Dictionary of English v.0.48:

Eunuch \Eu"nuch\, n. [L. eunuchus, Gr. ?, prop., keeping or
   guarding the couch; ? couch, bed, + ? to have, hold, keep.]
   A male of the human species castrated; commonly, one of a
   class of such persons, in Oriental countries, having charge
   of the women's apartments. Some of them, in former times,
   gained high official rank. Eunuch

The Collaborative International Dictionary of English v.0.48:

Eunuch \Eu"nuch\, Eunuchate \Eu"nuch*ate\, v. t. [L. eunuchare.]
   To make a eunuch of; to castrate. as a man. --Creech. Sir. T.
   Browne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eunuch
    n 1: a man who has been castrated and is incapable of
         reproduction; "eunuchs guarded the harem" [syn: eunuch,
         castrate]