Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A hole with the top part enlarged so that the head of a screw or bolt will lie flush with or below the surface.
  • noun A tool for making such a hole.
  • transitive verb To make a countersink on or in.
  • transitive verb To drive (a screw or bolt) into a countersink.

from The Century Dictionary.

  • noun A drill or brace-bit for countersinking, variously made, according as it is to be used on wood, iron, brass, etc.
  • noun An enlargement of a hole to receive the head of a screw or bolt.
  • noun The recess in the chamber of a gun into which the rim of the cartridge fits.
  • To form by drilling or turning, as a cavity in timber or other materials, for the reception of the head of a bolt or screw, a plate of iron, etc., in order that it may be nearly or quite flush with the surface: as, to countersink a hole for a screw.
  • To cause to sink in any other body so as to be nearly or quite flush with its surface: as, to countersink a screw or bolt by making a depression for its head.

from the GNU version of the Collaborative International Dictionary of English.

  • transitive verb To chamfer or form a depression around the top of (a hole in wood, metal, etc.) for the reception of the head of a screw or bolt below the surface, either wholly or in part.
  • transitive verb To cause to sink even with or below the surface.
  • noun An enlargement of the upper part of a hole, forming a cavity or depression for receiving the head of a screw or bolt.
  • noun A drill or cutting tool for countersinking holes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun a conical recess, typically machined around a hole to admit a screw so that it sits flush with a surface.
  • verb transitive to create such a conical recess.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a bit for enlarging the upper part of a hole
  • verb insert (a nail or screw below the surface, as into a countersink)
  • noun a hole (usually in wood) with the top part enlarged so that a screw or bolt will fit into it and lie below the surface

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

from counter + sink

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