Messy means disorganized, untidy, or chaotic. A messy bedroom has clothes scattered on the floor, books piled everywhere, and a desk buried under papers. A messy eater gets food on their face, hands, and shirt. A messy situation is complicated and hard to sort out, like when three friends have a disagreement and nobody can quite remember who said what.

Some mess comes from carelessness, but not all messiness is bad. Art projects are often messy: paint splatters, clay crumbles, and glue gets everywhere. Scientific experiments can be messy too. The key difference is whether you clean up afterward and whether the mess serves a purpose.

When something gets messier, it becomes harder to manage or understand. A simple plan that keeps getting more complicated becomes messier. Handwriting that's hard to read is messy. A messy problem has no clear solution.

People sometimes use messy to describe emotions or relationships that feel confusing or uncomfortable, like a messy argument where everyone ends up hurt. The opposite of messy is neat, tidy, or organized: everything in its place and easy to understand.