Countersink

a. [Lat. contra, and Eng. sink.] To widen the upper part of a hole in wood, metal, ., for the reception of something, as the head of a screw or bolt. -n. The widened part of an orifice made for the insertion of a screw, bolt, . (Joinery.) A bit or drill, for widening the upper part of a hole in wood or metal, for the head of a screw or pin, and having a conical head. Those for wood have one cutter in the conic surface, and have the cutting edge more remote from the axis of the cone than any other part of the surface. C. for bra have 11 or 12 cutters round the conic surface, so that the horizontal section represents a circular saw. These are called rose. The conic angle at the vertex is about 90 degrees. C. for iron have two cutting edges, forming an obtuse angle. Counter-slope, n . An overhanging slope. Counter-statement, n. A statement of an opposite character to one previously made.