To enroll means to officially sign up or register for something, usually a class, school, or program. When you enroll in fifth grade, your parents fill out forms and provide information so the school adds you to its list of students. When someone enrolls in piano lessons, they commit to attending regularly and become an official member of the class.

The word emphasizes making something official. You might think about joining the soccer team, but you're not really part of it until you enroll by signing up and paying any fees. Schools track their enrollment numbers to know how many students they have. Companies offer enrollment periods when employees can sign up for health insurance or retirement plans.

Parents usually enroll their children in school, but as you get older, you'll enroll yourself in college courses, workshops, or activities. The act of enrolling comes with responsibilities: once you're enrolled, you're expected to participate and follow through. If you later decide to leave, you might withdraw or unenroll, which is the opposite process.