counterbore

Etymology

From counter- (“against”) +‎ bore (“hole”).

Noun

counterbore (plural counterbores)

1. A cylindrical recess, typically machined around a hole to admit a screw so that it sits flush with a surface.
2. The tool with which a counterbore is machined.

Verb

counterbore (third-person singular simple present counterbores, present participle counterboring, simple past and past participle counterbored)

1. (transitive) To create such a cylindrical recess.

See also

• countersink
• spotface