'Topaz' definitions:

Definition of 'topaz'

noun

A yellow quartz [syn: topaz, false topaz, common topaz]

noun

A mineral (fluosilicate of aluminum) that occurs in crystals of various colors and is used as a gemstone

noun

A light brown the color of topaz [syn: tan, topaz]

From: GCIDE

Topaz \To"paz\, n. [OE. topas, F. topaze, L. topazos, or topazion, a kind of precious stone, Gr. to`pazos, topa`zion; possibly akin to Skr. tap to glow (cf. Tepid). According to some, the name is from Topazos, a small island in the Red Sea, where the Romans obtained a stone which they called by this name, but which is the chrysolite of the moderns.]
1. (Min.) A mineral occurring in rhombic prisms, generally yellowish and pellucid, also colorless, and of greenesh, bluish, or brownish shades. It sometimes occurs massive and opaque. It is a fluosilicate of alumina, and is used as a gem. [1913 Webster]
2. (Zool.) Either one of two species of large, brilliantly colored humming birds of the genus Topaza ({Topaza pella} or Topaza pyra), of South America and the West Indies. [1913 Webster]
Note: The two tail feathers next to the central ones are much longer that the rest, curved, and crossed. The Throat is metallic yellowish-green, with a tint like topaz in the center, the belly is bright crimson, the back bright red. Called also topaz hummer. [1913 Webster]
False topaz. (Min.) See the Note under Quartz. [1913 Webster]

Topaz Heb. pitdah (Ezek. 28:13; Rev. 21:20), a golden yellow or "green" stone brought from Cush or Ethiopia (Job 28:19). It was the second stone in the first row in the breastplate of the high priest, and had the name of Simeon inscribed on it (Ex. 28:17). It is probably the chrysolite of the moderns.