Merriam-Webster Collegiate Dictionary - binocular

 I. adjective  Date: 1738 of, relating to, using, or adapted to the use of both eyes ~ vision  • ~ity noun  • ~ly adverb  II. noun  Date: 1871  1. a ~ optical instrument  2. a handheld optical instrument composed of two telescopes and a focusing device and usually having prisms to increase magnifying ability — usually used in plural