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Webster's Dictionary (1865)

2 entries under this word

Countersink

Coun'ter-sink', v. t.

verbtransitive

v. t. [imp. & p. p. COUNTERSUNK; p. pr. & vb. n. COUNTERSINKING.]

  1. To form by drilling or turning, or otherwise, as a depression 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.
  2. To cause to sink so as to be even with or below the surface, by making an excavation for the head of;—said of a screw or bolt.

Coun'ter-sink, n.

noun

n. 1. A cavity or depression formed for receiving the head of a screw or bolt. 2. A drill or cutting-tool to enlarge the outer end of a hole in countersinking.