The word clutter can mean a messy jumble of objects. The disorganized clutter of shoes, hats, shirts, belts, jackets, and pants makes it impossible to find a thing in your closet!
Clutter can describe all those disorderly random things in your purse, but it can also refer to the random echoes that show up on a radar screen. The echos mix with other desired signals and can make it hard to track everything. As a verb, clutter is what you do when you fill up a space with a crazy mix of objects. You may clutter up the attic when you finally clean out that closet!