Dictionary.com
definitions
  • synonyms

opal

[oh-puh l]
noun
  1. 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.
  2. an iridescent variety of this that is used as a gem.
  3. a gem of this.
Show More

Origin of opal

1350–1400; Middle English < Latin opalus < Greek opállios opal, gem; probably from a source akin to Sanskrit upala precious stone

Opal

[oh-puh l]
noun
  1. a female given name.
Show More
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for opal

Contemporary Examples

Historical Examples


British Dictionary definitions for opal

opal

noun
  1. 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
Show More
Derived Formsopal-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

Word Origin and History for opal

n.

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.).

Show More
Online Etymology Dictionary, © 2010 Douglas Harper

opal in Science

opal

pəl]
  1. 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.
Show More
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.