What does countersunk mean?
Countersunk describes a screw, rivet, or similar fastener that has been driven into a cone-shaped recess so that its head lies flush with — or slightly below — the surface of the material around it. The recess itself may also be called countersunk. The term comes from the verb countersink, combining the prefix counter- (meaning 'against' or 'in opposition') with sink, and it belongs mainly to the practical vocabularies of woodworking, metalworking, and construction. Countersinking serves both aesthetic and functional purposes: a flush screw head leaves a smooth, snag-free finish, prevents clothing or skin from catching on protruding metal, and allows moving parts such as doors and drawers to close cleanly against frames. The word appears most often in attributive phrases like countersunk screw, countersunk hole, or countersunk head, and in specifications for furniture, decking, and machined parts. Its opposite condition is often described as a raised or protruding head.
(Of a screw or fastener) Fitted into a conical recess so that its head is level with or below the surrounding surface; also describing the recessed hole itself.
"Each countersunk screw was filled and painted over for a seamless finish."
Almost always used attributively before a noun, as in countersunk screw or countersunk hole.
Past participle of countersink: having formed a conical recess in a surface to receive the head of a screw, or driven such a screw into place.
"The joiner had countersunk every fixing before applying the varnish."
Used only as a past participle or passive form; the base form is countersink.
A countersunk screw sits perfectly flush with the wood around it — which is why you never feel one under your hand on a well-built table.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of countersunk
The word derives from the verb countersink, formed in English from the prefix counter-, indicating opposition or a reciprocal action, plus sink, from Old English sincan, meaning to subside or descend. The compound arose in the language of trades and crafts to describe cutting a hollow that lets a fastener's head sink below the surface, and its past participle countersunk came to function as an adjective. It has no notable cognates outside the Germanic root shared with ordinary sink and sunken.
Related word forms
How countersunk is actually used
Primarily technical vocabulary used in woodworking, carpentry, engineering, and hardware retail. It functions chiefly as an attributive adjective (a countersunk screw) rather than predicatively, and it is the past participle of "countersink" used adjectivally. In everyday speech people more often say a screw "sits flush" than call it countersunk.
Easily confused with countersunk
"Countersink" is the verb meaning to cut such a recess or drive the screw into one, while "countersunk" is its past participle and the adjective describing the resulting flush-fitting state.