countersink: Meaning and Definition of

coun•ter•sink

1. to enlarge the upper part of (a cavity), esp. by chamfering, to receive the cone-shaped head of a screw, bolt, etc.
2. to cause (the head of a screw, bolt, etc.) to sink into a prepared depression so as to be flush with or below the surface.

1. a tool for countersinking a hole.
2. a countersunk hole.