Qualifier is a casino term used in several variances of poker that refers to the requirements a player must meet in order to bet during a hand. In addition, if a player doesn’t meet said requirements, they are unable to win the pot.
The qualifier is most often used in Hi/Lo games, such as Omaha Hi/Lo and Stud Hi/Lo. Usually, games like those are known as Eight or Better, which is what you will need to qualify for the hand. However, keep in mind that the qualifier can change, depending on the casino you play in.
Qualifiers balance the power between high and low hands. As a result, players get to enjoy the game more, and high hands have a better incentive to continue playing when facing action from low ones.