any of a group of platy minerals, hydrous silicates of aluminum, magnesium, and iron, that expand markedly on being heated: used in the expanded state for heat insulation and as a plant growth medium.

Origin of vermiculite

An Americanism dating back to 1815–25; vermicul(ar) + -ite1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for vermiculite



any of a group of micaceous minerals consisting mainly of hydrated silicate of magnesium, aluminium, and iron: on heating they expand and exfoliate and in this form are used in heat and sound insulation, fireproofing, and as a bedding medium for young plants

Word Origin for vermiculite

C19: from vermicul (ar) + -ite 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for vermiculite

1814, from Latin vermiculari (from vermiculus, diminutive of vermis; see worm) + -ite.

Online Etymology Dictionary, © 2010 Douglas Harper