To commit means to dedicate yourself fully to something or to make a firm decision you intend to follow through on. When you commit to practicing piano every day, you're making a serious promise to yourself that you will practice regularly. When a team commits to winning the championship, every player dedicates their effort and focus to that goal.

The word carries weight because it implies you're binding yourself to something important. A person might commit to finishing a challenging book, to being a better friend, or to learning a difficult skill. Once you've committed, backing out can mean breaking your word. That's why people say they're “fully committed” or “totally committed” to emphasize they really mean it.

You can also commit something to memory by memorizing it so thoroughly that you remember it easily. And unfortunately, someone can commit a crime by doing something illegal, which shows how the word can mean carrying out an action, whether good or bad.

The noun form is commitment, which is both the act of committing and the dedication itself.