Tangency in a sentence as a noun

Is "tangency" really a widespread term for curvature discontinuity?

I feel like I have new gear knowledge from reading this post, despite having read hundreds of pages about gears and watched hours of gears videos previously; it happens to be something I can state, namely that the pressure angle always needs to point at the point of tangency of the pitch circles.

Tangency definitions

noun

the state of being tangent; having contact at a single point or along a line without crossing

noun

(electronics) a junction where things (as two electrical conductors) touch or are in physical contact; "they forget to solder the contacts"

See also: contact