What is a dioptric telescope, fitted with two tubes joining, so as to enable a person to view an object with both eyes at once; a double- barreled field glass or an opera glass called?

binocle — A dioptric telescope, fitted with two tubes joining, so as to enable a person to view an object with both eyes at once; a double- barreled field glass or an opera glass. (Webster's 1913.)

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