The word “lemma” comes from the Greek “lēmma,” which means “something assumed.” This definition applies most aptly to the logic context, in which a lemma is a supporting proposition in a larger argument. Linguists adopted the term, and this usage is how lemma is currently getting the spotlight: in AI and natural language processing (NLP). In a dictionary, a lemma is the base word. For example, there can be variants of a verb, including “running,” “ran,” and “runs,” but the lemma is “run.” For an adjective, “good” is the lemma of “better” and “best.” A good deal of training AI to understand language involved parsing language into lemmas and mapping various contexts.