what exactly is a "pet" in Swarm?

there's this Yuumi buff that lets your pets deal 50% more damage (Emotional Support Pet). but it doesn't actually specify what a pet is. I assume that the Yuumi weapon is a pet, but there has to be something else, right? maybe Illaoi's tentacles?

as far as I know pets aren't mentioned anywhere else in this game, so it's kinda weird Riot just mentions pets and expects people to know what they mean