The term originates from the name of the ancient region of Sumer, located in southern Mesopotamia (modern-day Iraq). The name 'Sumer' itself comes from Akkadian Šumeru, which was the Akkadian name for the land and its people. The English word 'Sumerian' is formed by appending the English adjectival suffix '-ian' (from Latin -ianus) to this base, following a standard pattern for creating demonyms and relational adjectives (e.g., Italian, Egyptian). Thus, 'Sumerian' literally means "of or pertaining to Sumer," directly linking the modern scholarly term to the ancient civilization it describes.

This is a proper noun derived from a toponym. It is not productively formed from separable English morphemes. The base 'Sumer' is the ancient geographical name, and the suffix '-ian' is a common English denominal suffix forming adjectives and nouns meaning "belonging to, relating to, or originating from."