• A man whose wife is unfaithful; the husband of an adulteress, a paternity fraud victim. A man that has been lied to about the child's paternity (intentional or unintentional).
• The word originates from the habit of the female cuckoo bird, which lays her eggs in the nests of other birds to be hatched by them. In the human world, mothers cause their child to be deceive about his or her paternal heritage by similar actions.

The above official definitions are slightly vague. A cuckold by our definition is a man that either is forced to allow or willingly allows his wife to have sex with another man or men. Often watching or even participating in the sexual acts. In some cases the woman is impregnated by another man, but typically it's more about sex and humiliation of the husband or boyfriend.