countersink (
http://definr.com/countersink)
n 1: 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
2: a bit for enlarging the upper part of a hole [syn:
counterbore,
countersink bit]
v : insert (a nail or screw below the surface, as into a
countersink) [syn:
set]