opal

[ oh-puhl ]

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.

  1. a gem of this.

Origin of opal

1
1350–1400; Middle English <Latin opalus<Greek opállios opal, gem; probably from a source akin to Sanskrit upala precious stone

Other definitions for Opal (2 of 2)

Opal
[ oh-puhl ]

noun
  1. a female given name.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use opal in a sentence

  • The sun jewelled the clear part of it with diamonds, and the strange milky glacier part of it with opals.

    Katharine Frensham | Beatrice Harraden
  • Alice regarded the opals on her fingers (she was born in October) with a pleased yet humorous smile.

    The Beauty | Mrs. Wilson Woodrow
  • And he saw socks that were as scandalously brilliant as spun turquoises or knitted opals.

    What Will People Say? | Rupert Hughes
  • The lama looked forth, a hand on either sill, with eyes that shone like yellow opals.

    Kim | Rudyard Kipling
  • She turned away, gazing across the wide stretch of river dotted with its shifting opals and pearls.

    The Silver Poppy | Arthur Stringer

British Dictionary definitions for opal

opal

/ (ˈəʊpəl) /


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

Origin of opal

1
C16: from Latin opalus, from Greek opallios, from Sanskrit upala precious stone

Derived forms of opal

  • opal-like, adjective

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

Scientific definitions for opal

opal

[ ōpəl ]


  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.

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