countersink

countersink is a   Verb

Definition:

[1] To chamfer or form a depression around the top of (a hole in wood, metal, etc.) for the reception of the head of a screw or bolt below the surface, either wholly or in part; as, to countersink a hole for a screw.

[2] To cause to sink even with or below the surface; as, to countersink a screw or bolt into woodwork.

Synonyms: