1. A word that refers to a part of what another word refers to; such as, in the relationship between leg and ankle, "ankle" is a meronym; in the relationship between brim and hat, "brim" is a meronym; and "finger" is a meronym of hand because a finger is part of a hand; and "sleeve" and "cuff" are meronyms of shirt.
2. A term midway between two opposites; for example, "flat" between convex and concave; as well as, "present" between past and future.