Making a commitment involves dedicating yourself to something, like a person or a cause. Before you make a commitment, think carefully. A commitment obligates you to do something.
Some commitments are large, like marriage. When you take a job, you're making a commitment to show up and do the job well, and your employer makes a commitment to pay you. There are smaller commitments too. If you said you'd meet a friend at six, that's a commitment — show up or your friend will be mad. You also can speak of commitment as a quality. Staying after school for a study group shows your commitment to good grades.