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.
Countersink
(Coun"ter*sink`), n.
1. An enlargement of the upper part of a hole, forming a cavity or depression for receiving the head of a
screw or bolt.
In the United States a flaring cavity formed by chamfering the edges of a round hole is called a countersink,
while a cylindrical flat-bottomed enlargement of the mouth of the hole is usually called a conterbore.
2. A drill or cutting tool for countersinking holes.
