opal

[ oh-puh l ]
/ ˈoʊ pəl /

noun

a mineral, an amorphous form of silica, SiO2 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

Definition for opal (2 of 2)

Opal

[ oh-puh l ]
/ ˈoʊ pəl /

noun

a female given name.
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Examples from the Web for opal

British Dictionary definitions for opal

opal

/ (ˈəʊpəl) /

noun

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: SiO 2 . n H 2 O

Derived Forms

opal-like, adjective

Word Origin for opal

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

Science definitions for opal

opal

[ ōpəl ]

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.