Pat is a casino term used among poker and blackjack players.
If you find yourself at a blackjack table and you hear someone use the term pat, you should know they are referring to an unbusted hand that has a card sum of at least 17 points, in which case the player shouldn’t be taking more cards.
If you are playing poker, draw poker to be more precise, the term pat has a very similar meaning. Namely, it refers to a hand where the player stands. In other words, a hand that does not need any more cards.