1) An instrument having a pair of decentered lenses (telescopes), one for each eye, used to magnify objects. 2) Using, relating to, or adapted to both eyes.
1738, "involving both eyes," from Fr. binoculaire, from L. bini "double" + ocularis "of the eye," from oculus "eye." The double-tubed telescopic instrument (1871, short for binocular glass) earlier was called a binocle (1696).