Countersink vs. Counterbore

Countersinknoun

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

Countersinkverb

(transitive) To create such a conical recess.

Countersinkverb

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

Countersinkverb

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.

Countersinkverb

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

Countersinknoun

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

Countersinknoun

A drill or cutting tool for countersinking holes.

Countersinknoun

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

Countersinknoun

a bit for enlarging the upper part of a hole

Countersinkverb

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

Countersink

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).

Counterborenoun

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

Counterborenoun

The tool with which a counterbore is machined.

Counterboreverb

(transitive) To create such a cylindrical recess.

Counterborenoun

A flat-bottomed cylindrical enlargement of the mouth of a hole, usually of slight depth, as for receiving a cylindrical screw head.

Counterborenoun

A kind of pin drill with the cutting edge or edges normal to the axis; - used for enlarging a hole, or for forming a flat-bottomed recess at its mouth.

Counterboreverb

To form a counterbore in, by boring, turning, or drilling; to enlarge, as a hole, by means of a counterbore.

Counterborenoun

a bit for enlarging the upper part of a hole

Counterbore

A counterbore (symbol: ⌴) is a cylindrical flat-bottomed hole that enlarges another coaxial hole, or the tool used to create that feature. A counterbore hole is typically used when a fastener, such as a socket head cap screw, is required to sit flush with or below the level of a workpiece's surface.