noun
: a plant having a part that may be used in place of soap: as
a. : a California plant ( Chlorogalum pomeridianum ) of the family Liliaceae
b. : soapwort 1
c. : any of several plants of the genera Agave, Yucca, and Zigadenus found in southwestern United States and adjacent Mexico
d. : a soapberry ( Shepherdia canadensis ) having leaves that are silvery on the lower surface