Solution 1:

There isn't a single word but, grammatically, we call that "degrees of comparison".

Degrees of comparison refers to adjectives being written in different forms to compare one, two or more nouns which are words describing persons, places and things. The three different forms of comparison are the positive, the comparative and the superlative.

Rules and exceptions on how to form the comparative and superlative degrees has been the subject of several questions here. Rules for single-word comparatives and superlatives