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
   "He used a countersink bit to create a smooth finish for the screw heads"
    
2. A bit for enlarging the upper part of a hole
   "The machinist used a countersink to create a recess for the bolt head";
   - counterbore, countersink bit

1. Insert (a nail or screw below the surface, as into a countersink)
   "He countersunk the screws to create a smooth finish";
   - set

Derived forms: countersunk, countersinks, countersinking

Type of: bit, bury, hole, sink

Encyclopedia: Countersink