• synonyms


noun Geology.
  1. the assemblage of rocks, rich in silica and alumina, that comprise the continental portions of the upper layer of the earth's crust.
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Compare sima1.

Origin of sial

1920–25; < German, equivalent to Si(licium) silicium + Al(uminium) aluminum
Related formssi·al·ic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for sial


  1. the silicon-rich and aluminium-rich rocks of the earth's continental upper crust, the most abundant individual rock being granite
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Derived Formssialic (saɪˈælɪk), adjective

Word Origin

C20: si (licon) + al (uminium)
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