Litter is rubbish that is left lying around outside.

A litter of things is a quantity of them that are lying around in a disorganized way.

If a number of things litter a place, they are scattered untidily around it or over it.

If something is littered with things, it contains many examples of it.

A litter is a group of animals born to the same mother at the same time.

Litter is a dry substance that you put in the container where you want your cat to go to the toilet.