- to enlarge the upper part of (a cavity), especially by chamfering, to receive the cone-shaped head of a screw, bolt, etc.
- to cause (the head of a screw, bolt, etc.) to sink into a prepared depression so as to be flush with or below the surface.
- a tool for countersinking a hole.
- a countersunk hole.
Origin of countersink
Examples from the Web for countersunk
Historical Examples of countersunk
Two holes are bored and countersunk for screws to hold the post and handle.Mission Furniture
H. H. Windsor
Holes are bored and countersunk at the places shown in the drawing.
Holes are bored in the front piece of the cart and countersunk on the inner side.
Two holes are bored and countersunk for the screws which hold it to the mill base.
Holes for the screws at the ends were bored and countersunk.Carpentry and Woodwork
Edwin W. Foster
- 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
- to drive (a screw) or sink (a bolt) into such an enlarged hole
- Also called: countersink bit a tool for countersinking
- a countersunk depression or hole