Wordorigins.org

The Hawkeye State gets its name from the French version of a Dakota Sioux tribe. The Dakota spelling varies, being given as Ayuhwa, Ouaouia, Aiouez, and Ioways. The name means “sleepy ones.”

The tribe bequeathed its name to the Iowa River and the river in turn gave its name to the territory.

(Sources: Illustrated Dictionary of Place Names; Webster’s Third New International Dictionary)