Is Identicalness a Real Word?

The quality or condition of being exactly the same as something else: identity, oneness, sameness, selfsameness.

What's the root word for identical?

It makes sense then, that the word identical has linguistic roots in the Latin word idem, meaning "the same."

What do you mean by corresponding?

1a : having or participating in the same relationship (such as kind, degree, position, correspondence, or function) especially with regard to the same or like wholes (such as geometric figures or sets) corresponding parts of similar triangles.