What does monocular mean?
Monocular describes anything that relates to one eye or uses vision through only one eye. The adjective is used in medicine and optics for monocular vision, meaning that a person sees with sight in only one eye, and in discussions of monocular instruments such as small telescopes. As a noun, a monocular is an optical viewing device used with one eye; the word can also denote a person who has sight in only one eye, although that use is less frequent. The term contrasts with binocular, which means involving or intended for both eyes. Monocular is especially associated with astronomy, wildlife observation, and situations in which one eye is covered or otherwise unavailable. Its Greek-derived name combines roots meaning “one” and “eye,” making its basic meaning straightforward.
Relating to one eye, using one eye, or involving vision through only one eye.
"The report notes that the patient has monocular vision."
Most often used in technical, medical, or optical contexts.
An optical instrument, especially a small telescope, intended to be used with one eye.
"He raised the monocular and searched the distant shoreline."
The word can also refer to a person with sight in only one eye, though the instrument sense is generally the more specialized modern use.
The plural is used when referring to more than one one-eyed viewing instrument.
"The observers set out several monoculars before the eclipse began."
From the Greek roots for “one” and “eye,” monocular literally means “one-eyed”—and it is the word astronomers and spectators use for a telescope designed to be looked through with just one eye.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does monocular come from?
Monocular comes from the Latin monocularis, formed from Greek monos, “one,” and Latin oculus, “eye.” The sense “having one eye” developed before the word came to describe optical instruments used with one eye. It shares the element oculus with words such as binocular, while the “one” element is related to the first element of English words such as monarch and monogram.
Related word forms
How monocular is actually used
The adjective is common in technical and medical contexts, especially in discussions of vision, instruments, and observation. The noun is less frequent and may refer to a one-eyed person as well as a one-eyed viewing instrument, depending on context.
Easily confused with monocular
Monocular relates to one eye or a one-eyed viewing device, whereas binocular describes something intended for or involving both eyes.
A monocle is a single eyeglass lens worn before one eye, while a monocular is a complete optical instrument, often a small telescope, used for viewing with one eye.