Definition of "counterbore" []

• A cylindrical recess, typically machined around a hole to admit a screw so that it sits flush with a surface. (noun)
• The tool with which a counterbore is machined. (noun)
• To create such a cylindrical recess. (verb)

Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License

• "- Did he set the correct rotational speed and were counterbore diameter and depth correct?"
• "- Did the trainee countersink/counterbore both sides of a through hole properly?"
• "Counterboring/countersinking with counterbore/countersink and turning tool1."