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[oh-puh l] /ˈoʊ pəl/
a mineral, an amorphous form of silica, SiO 2 with some water of hydration, found in many varieties and colors, including a form that is milky white.
an iridescent variety of this that is used as a gem.
a gem of this.
Origin of opal
1350-1400; Middle English < Latin opalus < Greek opállios opal, gem; probably from a source akin to Sanskrit upala precious stone


[oh-puh l] /ˈoʊ pəl/
a female given name. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for opal
Contemporary Examples
Historical Examples
  • The hues of the opal, the light of the diamond, are not to be seen if the eye is too near.

    Essays, First Series Ralph Waldo Emerson
  • She was like an opal—all sparkle when you move it, and at rest dull, most undeniably dull.

    Audrey Craven May Sinclair
  • To live in Venice is like being domesticated in the heart of an opal.

    Italy, the Magic Land Lilian Whiting
  • The top of the mountain, like that of Shasta, in direct sunlight is an opal.

  • There was also an Australian opal and an Asian emerald, the latter greener than the grass.

    The Paliser case Edgar Saltus
  • The moon, ringed by a halo, shone like an opal in the milk-white sky.

    The Child of Pleasure Gabriele D'Annunzio
British Dictionary definitions for opal


an amorphous, usually iridescent, mineral that can be of almost any colour, found in igneous rocks and around hot springs. It is used as a gemstone. Composition: hydrated silica. Formula: SiO2.nH2O
Derived Forms
opal-like, adjective
Word Origin
C16: from Latin opalus, from Greek opallios, from Sanskrit upala precious stone
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
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Word Origin and History for opal

1590s, from Middle French opalle (16c.), from Latin opalus (Pliny), supposedly from Greek opallios, possibly ultimately from Sanskrit upala-s "gem, precious stone." Used in Middle English in Latin form (late 14c.).

Online Etymology Dictionary, © 2010 Douglas Harper
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opal in Science
A usually transparent mineral consisting of hydrous silica. Opal can occur in almost any color, but it is often pinkish white with a milky or pearly appearance. It typically forms within cracks in igneous rocks, in limestones, and in mineral veins. It also occurs in the silica-rich shells of certain marine organisms. Chemical formula: SiO2·nH2O.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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