Yu·ma 1 (yo?o?m?)n. pl. Yuma or Yu·mas See Quechan.[Spanish, from O’odham yuumi.]Yu·ma 2 (yo?o?m?) A city of southwest Arizona on the Colorado River. It grew as a river crossing during the California gold rush in the mid-1800s.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.