What is a cuckold male?

In traditional usage a cuckold is a man who's wife/girlfriend engages in sexual activity with another male. In Word connotes that the cuckold is deceived and unwilling (as opposed to a "wittol," meaning a knowing cuckold reconciled to the situation.) It appears often in medieval, Elizabethan, and Restoration literature and is also used in legal proceedings in many English speaking countries.

In contemporary usage it is also common in the BDSM fetish community to denote a fetish in which a person (usually but not always male) gets a masochistic sexual thrill from their partner having sex with another person. In this usage a "cuckold male" would be a man who has such a fetish. (The use of the term "cuckold" for women with analogous masochistic inclinations is rarer but not unheard of.)