countersink verb & noun. ['kaʊntǝsɪŋk] L18.
[from COUNTER- 1 + SINK verb.]
A. verb trans. Pa. t. & pple -sunk [-sʌŋk].
1. Sink the head of (a screw, bolt, etc.) in a countersink so that it does not protrude. L18.

2. Enlarge the outer part of (a drilled hole) by bevelling the edge. Cf. earlier COUNTERSUNK. M19.
b. noun.
1. A tool for countersinking. L18.

2. A conical enlargement of the outer part of a drilled hole for receiving the head of a screw etc. M19.

[TahlilGaran] English Dictionary ▲