The term "ex" is an abbreviation for "ex-partner" or "ex-boyfriend/girlfriend." It refers to someone with whom you were in a romantic or intimate relationship in the past but are no longer together. The relationship could have ended due to a breakup or a mutual decision to part ways.
The term "ex" is commonly used to describe a former romantic partner, and it can apply to various types of relationships, such as ex-boyfriend, ex-girlfriend, ex-husband, or ex-wife, depending on the context. It's important to note that the term "ex" usually implies that the relationship has ended, and the individuals involved are no longer romantically involved.