The word cramp has two main meanings:

1. A sudden, painful tightening of a muscle that you can't control. When you get a cramp in your leg during a soccer game, the muscle contracts hard and won't relax, making it difficult to keep playing. Swimmers sometimes get cramps in their calves. These muscle cramps usually happen when you're dehydrated, tired, or using a muscle intensely. The sharp pain can make you stop whatever you're doing until the muscle finally releases. You might also hear about stomach cramps, which are painful squeezes in your belly, often from eating something that disagreed with you or from being nervous.
2. To restrict or squeeze something into too small a space. When five people try to ride in a car meant for four, they feel cramped because there isn't enough room to sit comfortably. A cramped apartment feels crowded and tight. You might also say that having to wear formal clothes cramps your style if you prefer casual clothing, or that too many rules cramp your creativity. When space or freedom feels limited and uncomfortable, that's what it means to be cramped.