kɹaʊn ˈd͡ʒæk.ɪt ˈd͡ʒækɪt (dentistry) dental appliance consisting of an artificial crown for a broken or decayed tooth tomorrow my dentist will fit me for a crown a type of fortification, like a hornwork, but consisting of a full bastion with the walls on either side ending in half-bastions from which longer flank walls run back towards the main fortress. The crownwork was used to extend the fortified area in a particular direction often in order to defend a bridge, prevent the enemy occupying an area of high ground, or simply strengthen the overall fortifications in the expected direction of attack.