D defs.my
Entry 3 senses Webster, 1913

Countersunk

/(-s?nk`)/ · Coun·ter·sunk · IPA
01 p. p. & a. Chamfered at the top; -- said of a hole.
  1. 1.
    Chamfered at the top; -- said of a hole.
  2. 2.
    Sunk into a chamfer; as, a countersunk bolt.
  3. 3.
    Beveled on the lower side, so as to fit a chamfered countersink; as, a countersunk nailhead.