The Collaborative International Dictionary of English v.0.48:

Cowfish \Cow"fish`\ (kou"f[i^]sh`), n. (Zool.)
   (a) The grampus.
   (b) A California dolphin (Tursiops Gillii).
   (c) A marine plectognath fish (Ostracoin quadricorne, and
       allied species), having two projections, like horns, in
       front; -- called also cuckold, coffer fish,
       trunkfish.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cuckold \Cuck"old\, v. t. [imp. & p. p. Cuckolded; p. pr. &
   vb. n. Cuckolding.]
   To make a cuckold of, as a husband, by seducing his wife, or
   by her becoming an adulteress. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cuckold \Cuck"old\ (k?k"?ld), n. [OE. kukeweld, cokewold,
   cokold, fr. OF. coucoul, cucuault, the last syllable being
   modified by the OE. suffix -wold (see Herald); cf. F. cocu
   a cuckold, formerly also, a cuckoo, and L. cuculus a cuckoo.
   The word alludes to the habit of the female cuckoo, who lays
   her eggs in the nests of other birds, to be hatched by them.]
   1. A man whose wife is unfaithful; the husband of an
      adulteress. --Shak.
      [1913 Webster]

   2. (Zool.)
      (a) A West Indian plectognath fish (Ostracion
          triqueter).
      (b) The cowfish.
          [1913 Webster]

WordNet (r) 3.0 (2006):

cuckold
    n 1: a man whose wife committed adultery
    v 1: be sexually unfaithful to one's partner in marriage; "She
         cheats on her husband"; "Might her husband be wandering?"
         [syn: cheat on, cheat, cuckold, betray, wander]