Merriam-Webster Collegiate Dictionary - zeolite

 noun  Etymology: Swedish zeolit, from Greek zein to boil + -o- + Swedish -lit -lite, from French -lite — more at yeast  Date: circa 1777 any of various hydrous silicates that are analogous in composition to the feldspars, occur as secondary minerals in cavities of lavas, and can act as ion-exchangers; also any of various natural or synthesized silicates of similar structure used especially in water softening and as adsorbents and catalysts  • zeolitic adjective