A cuckold is a man who has been betrayed by his wife. If your wife cuckolds you, she is cheating on you with another man. Cuckolding is usually accompanied with humiliation. It can be because he has a useless, small dick, and is not satisfying her. The wife chooses whether the cuck watches and/or participates. It can include having the cuck service the man she is cheating with (known as a "bull) or clean her up orally when finished.
A hot wife is a married woman who has the freedom in her marriage to pursue sexual relationships with men other than her husband. Her husband has full knowledge of her activities and consents to them. This is NOT humiliation based.
I've seen a few "dominants" (note uncapped) say they are, or wish to be, cuckolded because they share their sub with other men.
The problem with that statement is that while both are ultimately consented to, cuckolding is mostly about humiliation. If it's not about humiliation, it's Hot Wife (or Slut) if you wish to change the terms.
Edit: To not leave out the girls.. the female equivalent of cuckold is cuckquean.
"A wife who is compliant in her fetish for her husband's unfaithfulness or adultery. The female equivalent of the male cuckold. Comes from the Old English word cwene, meaning Queen. The true cuckquean will be a willing participant in the sex act between the husband and the third part female and may be subjected to humiliation and degrading sexual acts by both husband and partner."
Credits: Nadia Charles