Crown: 1. In dentistry, the portion of the tooth that is covered by enamel. 2. Also in dentistry, a type of restoration that covers all or most of the natural tooth. 3. In anatomy, the top of the head, as in the crown-rump length of a fetus. 4. In obstetrics, when a generous portion of the fetal scalp (the crown) become visible at the vaginal opening during labor. Soon after the baby crowns, delivery usually occurs.