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.

2. (Zo["o]l.)Either one of two species of large, brilliantly colored humming birds of the Topaza, of South America and the West Indies.

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.

False topaz. (Min.) See the Note under Quartz.

Source: Webster's Revised Unabridged Dictionary (1913)