Having two eyes: as, “most animals are binocular,” Also binoculate.Referring to both eyes; suited for the simultaneous use of both eyes: as, a binocular telescope or microscope.n. An optical instrument, such as a field-glass, with two objectives and two eyepieces, adjusted so as to permit the simultaneous use of both eyes. The word binocular has almost entirely supplanted the older and grammatically preferable form binocle.