A group of kangaroos is called a mob, everyday working vocabulary in Australia rather than an old, obscure term. Kangaroo mobs are genuinely social units, typically made up of related females and their young, with dominant males coming and going to mate rather than staying as permanent group leaders.
Mob size varies enormously depending on species and food availability, from small family groups of a handful of kangaroos to loose aggregations of dozens gathered around a shared water source or grazing area during dry conditions. Living in a mob offers real safety benefits, more eyes watching for dingoes and other predators, and an early warning system when one kangaroo thumps the ground in alarm.
Bonus fact: a kangaroo’s powerful tail acts as a third leg for balance, and it’s strong enough to support the animal’s full body weight while it delivers a defensive kick with its hind legs.
“Mob” is the overwhelmingly standard term for kangaroos, though “troop” and “court” occasionally appear in older or more playful sources.
Related: Collective Nouns for Mammals · What Is a Group of Kangaroo Called?