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Webster 1913 Edition

Noun.

[

Hydro-

, 1 + Gr. [GREEK] to show, appear: cf. F.

hydrophane

(Min.)

A semitranslucent variety of opal that becomes translucent or transparent on immersion in water.

Noun.

[Gr. water, and to show.] In mineralogy, a variety of opal made transparent by immersion in water.