Relating to, based on, or involving comparison. Of or relating to the scientific or historical comparison of different phenomena, institutions, or objects, such as languages, legal systems, or anatomical structures, in an effort to understand their origins or relationships. Estimated by comparison; relative: a comparative newcomer. Grammar Of, relating to, or being the intermediate degree of comparison of adjectives, as better, sweeter, or more wonderful, or adverbs, as more softly. Grammar The comparative degree. Grammar An adjective or adverb expressing the comparative degree.