diopter

noun

di·​op·​ter dī-ˈäp-tər How to pronounce diopter (audio)
ˈdī-ˌäp-
: a unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length in meters

Examples of diopter in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Our tester found the twist-out eyecups and diopter worked well, but the objective lens caps were a tight fit. Scott Gilbertson, WIRED, 6 Oct. 2024 Current Clinical Trials and Outcomes Clinical trials have started on the effectiveness of spiral diopter lenses for correcting presbyopia. William A. Haseltine, Forbes, 26 Feb. 2024 Most of the visual effects, in terms of the clairvoyance, were done in camera with me and a diopter, making a lot of noise and smashing glass against glass and a flashlight. Simon Thompson, Forbes, 13 Feb. 2024 While keeping the left side covered, rotate the diopter dial on the right eyecup until the image is in focus. Katherine Alex Beaven, Travel + Leisure, 17 Jan. 2024 Ophthalmologists measure this distortion in diopters, which refer to the strength of the lens required to bring someone’s vision back to normal. Amit Katwala, WIRED, 22 Aug. 2023 Take note of different arm heights, the number of nose bridges included, and whether or not there is built-in diopter tuning for nearsightedness. Hunter Fenollol, Popular Mechanics, 20 June 2023 The non-locking diopter is a tad too loose, and the finish is a little slick—both minor quibbles. Dave Hurteau, Field & Stream, 10 May 2023 With the exception of a slightly loose, non-locking diopter dial, everything feels smooth and positive and well-finished. Dave Hurteau, Field & Stream, 10 May 2023

Word History

Etymology

diopter (an optical instrument), from Middle French dioptre, from Latin dioptra, from Greek, from dia- + opsesthai to be going to see — more at optic

First Known Use

circa 1864, in the meaning defined above

Time Traveler
The first known use of diopter was circa 1864

Dictionary Entries Near diopter

Cite this Entry

“Diopter.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diopter. Accessed 11 Dec. 2024.

Medical Definition

diopter

noun
di·​op·​ter
variants or chiefly British dioptre
: a unit of measurement of the refractive power of a lens equal to the reciprocal of the focal length in meters

More from Merriam-Webster on diopter

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!