[ verb, noun koun-ter-singk; verb koun-ter-singk ]
/ verb, noun ˈkaʊn tərˌsɪŋk; verb ˌkaʊn tərˈsɪŋk /

verb (used with object), coun·ter·sank, coun·ter·sunk, coun·ter·sink·ing.

to enlarge the upper part of (a cavity), especially by chamfering, to receive the cone-shaped head of a screw, bolt, etc.
to cause (the head of a screw, bolt, etc.) to sink into a prepared depression so as to be flush with or below the surface.


a tool for countersinking a hole.
a countersunk hole.

Nearby words

  1. countershading,
  2. countershaft,
  3. countershock,
  4. countersign,
  5. countersignature,
  6. counterspy,
  7. counterstain,
  8. counterstamp,
  9. counterstatement,
  10. counterstroke

Origin of countersink

First recorded in 1810–20; counter- + sink Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for countersunk

British Dictionary definitions for countersunk


/ (ˈkaʊntəˌsɪŋk) /

verb -sinks, -sinking, -sank or -sunk (tr)

to enlarge the upper part of (a hole) in timber, metal, etc, so that the head of a bolt or screw can be sunk below the surface
to drive (a screw) or sink (a bolt) into such an enlarged hole


Also called: countersink bit a tool for countersinking
a countersunk depression or hole
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012