countersink

American  

[koun-ter-singk, koun-ter-singk] / ˈkaʊn tərˌsɪŋk, ˌkaʊn tərˈsɪŋk /

verb (used with object)

countersank, countersunk, countersinking

1. to enlarge the upper part of (a cavity), especially by chamfering, to receive the cone-shaped head of a screw, bolt, etc.

2. 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.

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noun

1. a tool for countersinking a hole.

2. a countersunk hole.

countersink British  

/ ˈkaʊntəˌsɪŋk /

verb

1. 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

2. to drive (a screw) or sink (a bolt) into such an enlarged hole

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noun

1. Also called: countersink bit.  a tool for countersinking

2. a countersunk depression or hole

Etymology

Origin of countersink

First recorded in 1810–20; counter- + sink

Example Sentences

Each takes up the question of how American infamy functioned as an unexamined countersink to the easy legend of American virtue.

From Slate • Jun. 20, 2019

He had taught his sons to "fell a tree, sow, cultivate and harvest, save money, countersink a nail, make cider with a hand press, clean a gun, sail a boat, etc."

From Time Magazine Archive

When drilling holes in fiberglass, first drill a tiny pilot hole, then use a countersink bit to bevel the edges before drilling a larger hole.

From Time Magazine Archive

How about we countersink the nozzle, one side or the other or both?

From "October Sky" by Homer Hickam

“Was it the countersink that made it explode?” he asked.

From "October Sky" by Homer Hickam