Agave root

• "...mountain out of --- hill"
• Detergent root
• Root used as a substitute for soap
• Plant with detergent properties
• Plant used as soap
• Whac-___ (carnival game)
• Soap source
• Root used as soap in Mexico

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1831, from Mexican Spanish amole , from Nahuatl (Aztecan) amolli "soap-root."

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Amole \A*mo"le\, n. [Mex.] (Bot.) Any detergent plant, or the part of it used as a detergent, as the roots of Agave Americana , Chlorogalum pomeridianum , etc. [Sp. Amer. & Mex.]