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

Words nearby opal

opacification, opacify, opacity, opacus, opah, opal, opal glass, opalesce, opalescent, opaleye, opaline

Definition for opal (2 of 2)

Opal
[ oh-puh l ]
/ ˈoʊ pəl /

noun

a female given name.

Example sentences 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 of opal

opal-like, adjective

Word Origin for opal

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

Scientific definitions for opal

opal
[ ō′pəl ]

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.