Definition of cusp

• n. - A triangular protection from the intrados of an arch, or from an inner curve of tracery.
• n. - The beginning or first entrance of any house in the calculations of nativities, etc.
• n. - The point or horn of the crescent moon or other crescent-shaped luminary.
• n. - A multiple point of a curve at which two or more branches of the curve have a common tangent.
• n. - A prominence or point, especially on the crown of a tooth.
• n. - A sharp and rigid point.
• v. t. - To furnish with a cusp or cusps.