Talon

n.
  1. The claw of a predaceous bird or animal, especially the claw of a bird of prey.
  2. (Zoöl.) One of certain small prominences on the hind part of the face of an elephant's tooth.
  3. (Arch.) A kind of molding, concave at the bottom and convex at the top; -- usually called an ogee.
  4. The shoulder of the bolt of a lock on which the key acts to shoot the bolt.

When the concave part is at the top, it is called an inverted talon.