Well, a group of lions is a pride. I don't know if that applies universally to cats though.
another word for large group is clan.
choir or orchestra is another word for music group
caterball
Another word for gather or collect is... handle or group together.
Another word for religious group could be "faith community" or "religious organization."
Another word for study group is "learning circle" or "study session".
faction clique
The correct term for referring to a group of cats is 'clowder.' Interestingly, there are also two other valid ways to refer to a group of cats, other than just saying "group of cats" or "cats." Those other two terms are 'clutter' and 'glaring.' In addition to this, if one wants to refer to a group of wild cats, the correct terms are 'dowt' and 'destruction.' A male cat, when neutered, is called a "gib," when not, is called a "tom." Female cats are known as "molly." The word "cat" itself derives from the Old English "catt." Catt has its source in the Late Latin "catus," meaning: "domestic cat." This Late Latin word probably derives from an Afro-Asiatic word: "kaddîska," meaning "wild cat."
group
A group of witches is a coven.
well another word could be a party or a group
word abour