If something is mussy, it is untidy or messy.
Mussy can make people think of things being out of order or not clean.
Examples:
Her hair is mussy after playing outside.
The room is mussy because the toys are everywhere.
He doesn't like to wear mussy clothes.
The kitchen was so mussy, you couldn't find anything!
The cat made the house very mussy with its muddy paws.
I don't want to go in the mussy room because it's too dirty.