Unmanageable means too difficult or impossible to control, handle, or deal with effectively. When something becomes unmanageable, it has grown beyond your ability to keep it organized or under control.

A teacher might find a classroom unmanageable if students are talking over each other, ignoring instructions, and making it impossible to teach the lesson. A garden can become unmanageable when weeds take over faster than you can pull them. Long hair might feel unmanageable on a windy day when it keeps whipping into your face and tangling into knots no matter what you do.

The word often suggests that something started out manageable but grew too big, too complicated, or too wild. A small debt might be manageable, but if it grows and grows, it can become unmanageable. A few pets are manageable, but a house overrun with dozens of animals would be unmanageable.

The opposite is manageable: something you can handle with reasonable effort. When you break an unmanageable project into smaller pieces, you make it manageable again. If your homework feels unmanageable, tackling one subject at a time makes it manageable.