counterbore
noun, verb
Forms counterbores counterboring counterbored
- noun A cylindrical recess, typically machined at the mouth of a hole to admit a screw (such as a cap screw) so that the screw sits flush with a surface.
- noun The cutter used to cut such a recess. (Also used, at less depth, for spotfacing.)
- verb (transitive) To create such a cylindrical recess.
Synonyms
Etymology
From counter- (“against”) + bore (“hole”).
Webster’s 1913
- noun A flat-bottomed cylindrical enlargement of the mouth of a hole, usually of slight depth, as for receiving a cylindrical screw head.
- noun 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.
- verb To form a counterbore in, by boring, turning, or drilling; to enlarge, as a hole, by means of a counterbore.
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “counterbore”, CC BY-SA 4.0. Details