countersank

As a noun terms

is .

As a verb countersank is

(countersink).

As verbs the difference between countersang and countersank

is that countersang is (countersing) while countersank is (countersink).

As verbs the difference between countersunk and countersank

is that countersunk is while countersank is (countersink).

As an adjective countersunk

is (of a bolt or screw) that has a flat conical top allowing it to be inserted flush with a surface.

As verbs the difference between countersank and countersink

is that countersank is (countersink) while countersink is to create such a conical recess.

As a noun countersink is

a conical recess, typically machined around a hole to admit a screw so that it sits flush with a surface.