Wordorigins.org

This US state gets its name from the Alabama River, but where does the river get its name?

The answer is not known for certain, but it could come from the name of an Indian tribe whose name comes from the Choctaw alba, meaning plant or thicket, and amo, meaning cleaners or reapers. So the name of the tribe means cleaners of thickets.

(Source: Illustrated Dictionary of Place Names)