A confused disordered jumble of things.
Background echoes, from clouds etc., on a radar or sonar screen.
A group of cats; the collective noun for cats.
Clatter; confused noise.
To fill something with clutter.
To clot or coagulate, like blood.
To make a confused noise; to bustle.
To utter words hurriedly, especially (but not exclusively) as a speech disorder (compare cluttering).