Wordorigins.org

The name Arizona is native American, probably from the Papago arizonac, meaning little spring or few springs. Although there are other possibilities so this origin should not be taken as a certainty.

Many believe it to come from the Spanish arida (dry) + zona (area). This is certainly not the ultimate origin, although it is likely that this Spanish combination influenced the form and adoption of the word in both Spanish and English.

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