- (n.) 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.
- (v.t.) To form a counterbore in, by boring, turning or drilling; to enlarge, as a hole, by means of a counterbore.
- (n.) A flat-bottomed cylindrical enlargement of the mouth of a hole, usually of slight depth, as for receiving a cylindrical screw head.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). counterbore. Retrieved September 21, 2026, from http://smartdefine.org/counterbore/definitions/1992199 |
| Chicago | Webster's. 2011. "counterbore" http://smartdefine.org/counterbore/definitions/1992199 (accessed September 21, 2026). |
| Harvard | Webster's 2011, counterbore, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/counterbore/definitions/1992199>. |
| MLA | Webster's. "counterbore" 27 May 2011. Web. 21 September 2026. <http://smartdefine.org/counterbore/definitions/1992199> |