perlite

per·lite

also pearl·ite  (pûr′līt′)

n.

A natural volcanic glass similar to obsidian but having distinctive concentric cracks and a relatively high water content. In a fluffy heat-expanded form perlite is used as a lightweight aggregate, in fire-resistant insulation, and in soil for potted plants.

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[French (from perle, pearl, from Old French; see pearl¹) or German Perlit (from Perle, pearl, ultimately from Vulgar Latin *pernula).]

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per·lit′ic (pər-lĭt′ĭk) adj.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

perlite

(ˈpɜːlaɪt) or

pearlite

n

(Minerals) a variety of obsidian consisting of masses of small pearly globules: used as a filler, insulator, and soil conditioner

[C19: from French, from perle pearl¹]

perlitic, pearlitic adj

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

per•lite

(ˈpɜr laɪt)

n.

a volcanic glass in which concentric fractures impart a distinctive structure resembling masses of small spheroids, used as a plant growth medium.

[1825–35; < French; see pearl¹, -ite¹]

per•lit′ic (-ˈlɪt ɪk) adj.

Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.