1. A shrubby tropical American plant (Mimosa pudica) having mauve flower heads and bipinnately compound leaves with leaflets and leafstalks that fold and droop when touched. Also called touch-me-not.
2. Any of various similar plants, such as Cassia nictitans, of eastern and central North America.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.