n. A man married to an unfaithful wife.
tr.v. cuck·old·ed, cuck·old·ing, cuck·olds
To make a cuckold of.

[Middle English cokewald, from Anglo-Norman *cucuald, from cucu, the cuckoo, from Vulgar Latin *cucclus, from Latin cuclus.]
Word History: The allusion to the cuckoo on which the word cuckold is based may not be appreciated by those unfamiliar with the nesting habits of certain varieties of this bird. The female of some Old World cuckoos lays its eggs in the nests of other birds, leaving them to be cared for by the resident nesters. This parasitic tendency has given the female bird a figurative reputation for unfaithfulness as well. Hence in Old French we find the word cucuault, composed of cocu, “cuckoo, cuckold,” and the pejorative suffix -ald and used to designate a husband whose wife has wandered afield like the female cuckoo. An earlier assumed form of the Old French word was borrowed into Middle English by way of Anglo-Norman. Middle English cokewold, the ancestor of Modern English cuckold, is first recorded in a work written around 1250.

What a great word…