To realize something means to suddenly understand or become aware of it. When you realize you left your homework at home, that moment of recognition hits you: you weren't thinking about it, and then suddenly you know. A student might realize halfway through a test that they studied the wrong chapter, or realize during recess that their friend seemed upset earlier.

The word captures that specific moment when something clicks in your mind. You might come to realize that your little brother looks up to you more than you thought, or realize that the math problem isn't as hard as it seemed once you break it down. Sometimes people realize things gradually, and sometimes the realization arrives all at once.

Realize also means to make something real or achieve it. An inventor realizes her vision when she builds a working prototype. An athlete realizes his dream of making the Olympic team. When you realize your potential, you're actually achieving what you're capable of, turning possibility into reality.

The two meanings connect: you can't achieve a goal until you first realize (understand) what you're working toward. Both meanings involve something moving from unclear or unreal to clear and actual.