Definition of counterbore in English:


Syllabification: coun·ter·bore
Pronunciation: /ˈkountərˌbôr


  • 1A drilled hole that has a flat-bottomed enlargement at its mouth.
    More example sentences
    • In the new design, the holes are formed with a lead-in chamfer to facilitate pushpin insertion and a counterbore formed inside the hole that creates a shoulder to hold the pins in place.
    • A counterbore surrounds each rivet receiving opening in the flat bottom surface.
    • This is followed by a two-pass drilling operation to produce the counterbore and the bolthole.
  • 1.1A drill whose bit has a uniform smaller diameter near the tip, for drilling counterbores in one operation.


[with object] Back to top  
  • Drill a counterbore in (an object).
    More example sentences
    • The end of the sleeve inside the mount was shortened and counterbored to accommodate the 0.16 NA beam.
    • If the wood is thicker than three-fourths of an inch, you can either substitute longer screws or counterbore the interior surface of the door or drawer so that the screw head is recessed into the wood.
    • It is an optional tiebar style with mounting holes drilled and counterbored for 1/4 inch SHCS.

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a slit made by cutting with a saw