Countersang vs Countersank - What's the difference?

As verbs the difference between countersang and countersank

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

(head)

(countersing)

(biology, of a bird) To sing in response to the song of another

(head)

(countersink)

(en noun)

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

To create such a conical recess.

to countersink a hole for a screw

To cause to sink even with or below the surface.

to countersink a screw or bolt into woodwork