Word.ws English Dictionary

dioptre

dioptre is the alternative spelling of diopter.

Meaning of diopter

Noun

diopter (plural diopters)

  1. A unit of measure of the power of a lens or mirror, equal to the reciprocal of its focal length in meters. Myopia is diagnosed and measured in diopters.
  2. The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
  3. (dated) A lens element attached to the front of a photographic lens to shorten the lens's minimum focus distance; also called a "close-up filter".
  4. (obsolete) Any lens system, such as a telescope.
  5. (obsolete) A theodolite or similar surveyor’s angle measuring device.
  6. (obsolete) An alidade.

See all 8 meanings of diopter

Forms of dioptre

pluraldioptres

Questions about dioptre

What is dioptre the alternative spelling of?
Dioptre is the alternative spelling of diopter.

Words near dioptre in the dictionary

  1. dioptometer
  2. dioptometers
  3. dioptra
  4. dioptral
  5. dioptrate
  6. dioptre
  7. dioptres
  8. dioptric
  9. dioptrical
  10. dioptrically
  11. dioptrics

Source and license

Adapted from Wiktionary: dioptre (page history and authors); diopter (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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Cite this entry: “dioptre.” Word.ws, https://word.ws/dioptre. Based on Wiktionary, CC BY-SA 4.0.