Have an affair is a term used to describe a situation in which two people, who are usually in a committed relationship with someone else, engage in a romantic or sexual relationship. The crossword solutions for this term are CHEAT (5 letters) and HOST (4 letters). CHEAT is a verb meaning to be unfaithful to one's partner by engaging in a romantic or sexual relationship with someone else. HOST is a noun meaning the person who provides the location for an event or gathering.