1. A point or pointed end.
2. Anatomy.
   1. A pointed or rounded projection on the chewing surface of a tooth.
   2. A triangular fold or flap of a heart valve.
3. Mathematics. A point at which a curve crosses itself and at which the two tangents to the curve coincide.
4. Architecture. The point of intersection of two ornamental arcs or curves, such as the inner points of a trefoil.
5. Astronomy. Either point of a crescent moon.
6. A transitional point or time, as between two astrological signs.

[Latin cuspis, point.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.