| Noun | 1. | cusp - point formed by two intersecting arcs (as from the intrados of a Gothic arch)point - sharp end; "he stuck the point of the knife into a tree"; "he broke the point of his pencil" |
| 2. | cusp - a thin triangular flap of a heart valve flap - a movable piece of tissue partly connected to the body cardiac valve, heart valve - a valve to control one-way flow of blood | |
| 3. | cusp - small elevation on the grinding surface of a tooth tooth - hard bonelike structures in the jaws of vertebrates; used for biting and chewing or for attack and defense |