1. Collective Noun: When referring to a group of young animals, especially of a cat, dog, pig, or rodent, it is a collective noun. For example:
* "The mother cat watched over her litter of kittens."
2. Common Noun: When referring to garbage or discarded materials, it is a common noun. For example:
* "Please don't litter in the park."
So, the kind of noun "litter" is depends on the context.