cluttered (up) (with somebody/something) covered with, or full of, a lot of things or people, in a way that is untidy a cluttered room/desk (figurative) a cluttered mind opposite unclutteredExtra examples Her desk was cluttered with papers. The computer screen can become cluttered with windows. Don’t let your folder become cluttered up with papers you are not using. His apartment was small, cluttered and dirty. The study was cluttered with furniture.