Countersunk

Countersink \Coun"ter*sink`\ (koun"t[~e]r*s[i^][ng]k`; 277), v.
   t. [imp. & p. p. {Countersunk} (-s[u^][ng]k`); p. pr. & vb.
   n. {Countersinking}.]
   1. 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;
      as, to countersink a hole for a screw.
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   2. To cause to sink even with or below the surface; as, to
      countersink a screw or bolt into woodwork.
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Countersunk \Coun"ter*sunk`\ (-s?nk`), p. p. & a. from
   {Countersink}.
   1. Chamfered at the top; -- said of a hole.
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   2. Sunk into a chamfer; as, a countersunk bolt.
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   3. Beveled on the lower side, so as to fit a chamfered
      countersink; as, a countersunk nailhead.
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