binoculars(n = noun.artifact) field glasses, opera glasses - an optical instrument designed for simultaneous use by both eyes;
is a kind of optical instrument
has parts: eyepiece, ocular

binoculars, n.pl. an optical instrument with a lens for each eye, for viewing distant objects.

N  optical instruments, lens, meniscus, magnifier, sunglass, magnifying glass, hand lens, microscope, megascope, tienoscope, spectacles, specs, glasses, barnacles, goggles, eyeglass, pince-nez, monocle, reading glasses, bifocals, contact lenses, soft lenses, hard lenses, sunglasses, shades, periscopic lens, telescope, glass, lorgnette, spyglass, opera glass, binocular, binoculars, field glass, burning glass, convex lens, concave lens, convexo-concave lens, coated lens, multiple lens, compound lens, lens system, telephoto lens, wide-angle lens, fish-eye lens, zoom lens, optical bench, astronomical telescope, reflecting telescope, reflector, refracting telescope, refractor, Newtonian telescope, folded-path telescope, finder telescope, chromatoscope, X-ray telescope, radiotelescope, phased-array telescope, Very Large Array radiotelescope, ultraviolet telescope, infrared telescope, star spectroscope, space telescope, altazimuth mount, equatorial mount, refractometer, circular dichroism spectrometer, interferometer, phase-contrast microscope, fluorescence microscope, dissecting microscope, electron microscope, transmission electron microscope, scanning electron microscope, SEM, scanning tunneling electron microscope, objective lens, eyepiece, barrel, platform, focusing knob, slide, slide glass, cover glass, counting chamber, illuminator, light source, polarizer, reticle, cross-hairs, light pipe, fiber optics mirror, reflector, speculum, looking- glass, pier-glass, cheval-glass, rear-view mirror, hand mirror, one-way mirror, magnifying mirror, fun house, prism, diffraction grating, beam splitter, half-wave plate, quarter-wave plate, camera lucida, camera obscura, magic lantern, stereopticon, chromatrope, thaumatrope, stereoscope, pseudoscope, polyscope, kaleidoscope, photometer, eriometer, actinometer, lucimeter, radiometer, ligth detector, photodiode, photomultiplier, photodiode array, photocell, X-ray diffractometer, goniometer, spectrometer, monochrometer, UV spectrometer, visible spectrometer, Infrared spectrometer, Fourier transform infrared spectrometer, recording spectrometer, densitometer, scanning densitometer, two-dimensional densitometer, abdominoscope, gastroscope, helioscope, polariscope, polemoscope, spectroscope, abdominoscopy, gastroscopy, microscopy, microscopist.