The Collaborative International Dictionary of English v.0.48:

Sumerian \Su*me"ri*an\, a. [Written also Sumirian.]
   Of or pertaining to the region of lower Babylonia, which was
   anciently called Sumer, or its inhabitants or their language.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Sumerian \Su*me"ri*an\, n. [Written also Sumirian.]
   A native of lower Babylonia, anciently called Sumer.
   [Webster 1913 Suppl.]