Oh, if only Madame L had a picture of a CLOWDER of cats to go with this definition. (Hint, hint)
Yes, that's right, a "clowder" is a group of cats.
Here's a list of all kinds of groups of animals, with some of their traditional and made-up names.
Please note some of the other cute names for groups of cats: a clutter, a pounce, a dout, a nuisance, a glorying, and a glare. Wild cats are a destruction, and kittens are a litter (of course), an intrigue, and/or a kindle.