What is the collective name for a group of lions?

A group of lions is called a pride.

A pride is usually a social unit made up of related females, their cubs, and one or more adult males. The exact size and composition vary, but prides may contain several individuals to more than a dozen. Females commonly cooperate in hunting and in caring for cubs.

Lions are unusual among cats because they are strongly social. Most other living cat species generally live alone outside mating or family relationships. Cooperative living can help lions defend territory, protect young, and overwhelm prey, although it also creates competition over food and breeding opportunities.

The word pride is a collective term, not a biological rank or a fixed population measurement. A lion population contains multiple prides, and prides can split, merge, or change when males take over a territory. Male coalitions, often formed by brothers or unrelated allies, may jointly defend a pride from rivals.