Ŏp'er-ā-glāss, n.

noun

n. A short telescope with concave eye-lenses of low power, usually made double, or with a tube and set of glasses for each eye, and used at theaters and other places of public amusement to see objects with greater distinctness; a lorgnette.

An antique opera glass with two small telescopes joined by a central focusing mechanism.
Opera-glass.