Meanings
noundiopter (plural diopters)
plural diopters · alternative dioptra · alternative dioptre · alternative dioptry
- 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.
- The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
- datedartsA lens element attached to the front of a photographic lens to shorten the lens's minimum focus distance; also called a "close-up filter".
- obsoleteAny lens system, such as a telescope.
- obsoleteA theodolite or similar surveyor’s angle measuring device.
- obsoleteAn alidade.
- obsoleteAn instrument for drawing the skull by projections.
Synonyms & antonyms
nouna unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculists
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Synonym sets from Open English WordNet, CC BY 4.0.
Origin
- Ancient Greekδιόπτρα
- Latindioptra
- Englishdiopter
From Latin dioptra, from Ancient Greek διόπτρα (dióptra).
More words from Latin, Ancient Greek
Full word history & related roots →Translations
Basque dioptria
- dioptriaunit of measure
Bulgarian диоптър
- диоптър (dioptăr)unit of measure
Catalan diòptria
- diòptriaunit of measure
Czech dioptrie
- dioptrieunit of measure
Finnish dioptria, diopteri
- dioptriaunit of measure
- diopteriunit of measure
- teodoliittitheodolite
German Dioptrie, Diopter
- Dioptrieunit of measure
- Diopterlens system
- Dioptertheodolite
Hungarian dioptria
- dioptriaunit of measure
Italian diottria
- diottriaunit of measure
Japanese ディオプトリ
- ディオプトリ (dioputoti)unit of measure
Polish dioptria
- dioptriaunit of measure
Portuguese dioptria
- dioptriaunit of measure
Russian дио́птрия
- дио́птрия (dióptrija)unit of measure
Spanish dioptría
- dioptríaunit of measure
Rhymes & wordplay
Anagrams
Cite this entry
APA
diopter. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/diopter
MLA
“diopter.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/diopter. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “diopter,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/diopter.
Source: diopter on Wiktionary, CC BY-SA 4.0.