verbWord forms: -sinks, -sinking, -sank or -sunk(transitive)
1.
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
2.
to drive (a screw) or sink (a bolt) into such an enlarged hole
noun
3. Also called: countersink bit
a tool for countersinking
4.
a countersunk depression or hole
counterbore in American English
(ˈkauntərˌbɔr, -ˌbour, ˈkauntərˈbɔr, -ˈbour)
Word forms: verb-bored, -boring
noun
1.
a tool for enlarging a drilled hole for a portion of its length, as to permit sinking a screw head
2.
the portion of the hole so enlarged
transitive verb
3.
to enlarge (a drilled hole) along part of the length of the hole by drilling witha bit having a greater diameter
Derived forms
counterborer
noun
Word origin
[1605–15; counter- + bore1]This word is first recorded in the period 1605–15. Other words that entered Englishat around the same time include: displacement, inverse, package, surface, turnover