having only one eye.
of, relating to, or for the use of only one eye: a monocular microscope.


a monocular instrument or device.

Origin of monocular

1630–40; < Late Latin monocul(us) one-eyed (see monocle) + -ar1
Related formsmo·noc·u·lar·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for monocular

Historical Examples of monocular

  • The little microscope was an excellent one, though only a monocular.

    Badge of Infamy

    Lester del Rey

  • Nystagmus occasionally occurs in monocular fixation (with exclusion of the other eye).

  • These are the retinal field of vision, the monocular field, and the binocular field.

    Visual Illusions

    Matthew Luckiesh

  • Even the doctor, himself a hardened man of the sea, showed a brilliant spark of emotion behind his monocular attic window.

    Plum Pudding

    Christopher Morley

  • Monocular, mon-ok′ū-lar, adj. with one eye only: fitted only for one eye at a time.

British Dictionary definitions for monocular



having to do with or using only one eye


a device for use with one eye, such as a field glass
Derived Formsmonocularly, adverb

Word Origin for monocular

C17: from Late Latin monoculus one-eyed
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for monocular

1630s, from Late Latin monoculus "one-eyed," from Greek monos "alone, single" (see mono-) + Latin oculus "eye" (see eye (n.)).

Online Etymology Dictionary, © 2010 Douglas Harper

monocular in Medicine




Having or affecting one eye only.
Having a single eyepiece, as certain microscopes or other optical instruments.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.