Definition of Cover
In the context of gambling, the most popular use of ‘cover’ is in sports betting, and it means to make good on a bet.
More specifically, cover usually refers to a point spread win. If a team were a 3-point favorite, which means that the bettor would spot the opponent three points, the favorite would need to win by four or more to cover the spread.
The term cover also refers to a full cover bet, which is a form of parlay. The distinction between a parlay and a full cover bet is that the cover must account for all available combinations, within context, rather than just two or more.