The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of a group of micaceous hydrated silicate minerals related to the chlorites and used in heat-expanded form as insulation and as a planting medium.
n. A hydrated silicate mineral which expands on heating; it is used in insulation and as a medium for planting
the GNU version of the Collaborative International Dictionary of English
n. A group of minerals having, a micaceous structure. They are hydrous silicates, derived generally from the alteration of some kind of mica. So called because the scales, when heated, open out into wormlike forms.
The Century Dictionary and Cyclopedia
n. In mineralogy, one of a group of hydrous silicates having a micaceous structure, and in most cases derived from the common micas by alteration.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. any of a group of yellow or brown hydrous silicate minerals having a micaceous structure
Word Usage
"The name vermiculite was created from the Latin word for worm, vermiculus."