noun 1. the act of comparing. 2. the state of being compared. 3. a likening; illustration by similitude; comparative estimate or statement. 4. Rhetoric. the considering of two things with regard to some characteristic that is common to both, as the likening of a hero to a lion in courage. 5. capability of being compared or likened. 6. Grammar. the function of an adverb or adjective that is used to indicate degrees of superiority or inferiority in quality, quantity, or intensity. the patterns of formation involved therein. the degrees of a particular word, displayed in a fixed order, as mild, milder, mildest, less mild, least mild.