Countersink vs. Counterbored — What's the Difference?

A countersink (symbol: ⌵) is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common use is to allow the head of a countersunk bolt, screw or rivet, when placed in the hole, to sit flush with or below the surface of the surrounding material (by comparison, a counterbore makes a flat-bottomed hole that might be used with a socket-head capscrew).

Simple past tense and past participle of counterbore

A hole with the top part enlarged so that the head of a screw or bolt will lie flush with or below the surface.

A tool for making such a hole.

To make a countersink on or in.

To drive (a screw or bolt) into a countersink.

A cylindrical recess, typically machined around a hole to admit a screw so that it sits flush with a surface.

(transitive) To create such a conical recess.

(transitive) To cause to sink even with or below the surface.

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.

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

An enlargement of the upper part of a hole, forming a cavity or depression for receiving the head of a screw or bolt.

A drill or cutting tool for countersinking holes.

A hole (usually in wood) with the top part enlarged so that a screw or bolt will fit into it and lie below the surface

A bit for enlarging the upper part of a hole

Insert (a nail or screw below the surface, as into a countersink)