cusp Definition

cusp
noun

1. geom.
A point formed by the meeting of two curves, corresponding to the point where the two tangents coincide.
2. astron.
Either point of a crescent Moon.
3. anatomy.
A sharp raised point on the grinding surface of a molar tooth.
4. astrol.
The point of transition between one sign of the zodiac and the next.
5. archit.
A projecting point found between arcs in Gothic tracery.

Derivative: cuspate
adj

Etymology: 16c: from Latin cuspis point.