Alternate (chiefly British) spelling of disorganize.

(Alternate spelling: disorganise).
To remove the organization from.

1. To make a mess of or create disorder in; SYN. mess up.
2. To eat in a mess hall, in the military.

1. When you mess up a place, you make it dirty or disorganized.
2. When you mess up a situation, you create problems. When you mess up a plan or arrangement, you interfere with it and prevent it from happening as planned. Mess up is similar to screw up.