A noun referring to a cat in the sitting position when all limbs are neatly curled underneath its body so they cannot be seen. It's origins come from the combination of the words "cat" and "egg" after observations were made regarding the similarity of the position to a chicken laying eggs. Witnessing such a site will immediately grant you everlasting happiness.
It can also be used as a verb. "to categg" is to be in this specific sitting position.
noun: I walked in my room and was surprised to find a categg on my bed.
Be careful, there is a categg on the floor behind you!
verb: Whiskers is currently categging next to me on the couch.