The term “one-gap” in poker usually refers to two cards which are consecutive but have a card missing in between them. This can be in the context of a straight draw (attempt to make a straight) or other hands.

For example, if you have a 7 and a 9 in hand, the eight (8) card is missing from between them. This hand is called a “one-gap” or as having one gap. In this case, to complete the straight, you need to get an 8 between the 7 and 9.

It’s important to remember that “one-gap” hands may be stronger than hands without gaps (for example, 6-7 or 8-9). They may have a lower chance of completing a hand on the river (last street), and, consequently, are more often less appealing to play.