1. A trailing or climbing spiny shrub (Euphorbia milii) native to Madagascar and cultivated as a houseplant, having showy flower clusters with usually red, petallike bracts.
2. The Christ's thorn.

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.