noun a sharp and rigid point.
2. cusp ·vt to furnish with a cusp or cusps.
3. cusp ·noun a prominence or point, especially on the crown of a tooth.
4. cusp ·noun the point or horn of the crescent moon or other crescent-shaped luminary.
5. cusp ·noun the beginning or first entrance of any house in the calculations of nativities, ·etc.
6. cusp ·noun a triangular protection from the intrados of an arch, or from an inner curve of tracery.
7. cusp ·noun a multiple point of a curve at which two or more branches of the curve have a common tangent.