NUM 极大的数目;庞大的数量 If you talk about a zillion people or things, you are emphasizing that there is an extremely large number of them. 极大的数目;庞大的数量 [informal, emphasis]
It's been a zillion years since I've seen her.
我已经有很多年没见过她了。
You can also use zillions as a quantifier.
There are zillions of things to look at or try out.