Countersunk

Coun″ter‐sunk′ (–s?nk′), p. p. & a. from Countersink. 1. Chamfered at the top; — said of a hole.

2. Sunk into a chamfer; as, a countersunk bolt.

3. Beveled on the lower side, so as to fit a chamfered countersink; as, a countersunk nailhead.