nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Any of various massive extinct edentates, especially of the genus Megatherium, inhabiting South America during the Pleistocene Epoch and related to the sloths. Also called giant ground sloth.