A group of 3 or more cats is called a “clowder.” Where did that come from?

According to Wiktionary, clowder was noted as being used in the English language in 1801. But it’s origin is much older. It began with the Old English word, clott (contemporary spelling: clot). Clott became clutter during the Middle English (1100-1500) period, which began because of the Norman Conquest in 1066. By 1167, Oxford University was founded and Cambridge followed in 1209. Both these institutions increased literacy and an expansion of the English language. Clutter became clowder, although currently, it’s not in common use.

These are also acceptable references to a group of 3 or more cats:
Cluster of cats
Clutter of cats
Destruction of cats
Dout of cats
Glaring of cats
Nuisance of cats
Pounce of cats — my kitty care favorite

To My Kitty Care, whether it’s one, two or a clowder of cats, we love them.