What is a unit employed by oculists in numbering glasses according to the metric system; a refractive power equal to that of a glass whose principal focal distance is one meter called?
dioptre — A unit employed by oculists in numbering glasses according to the metric system; a refractive power equal to that of a glass whose principal focal distance is one meter. (Webster's 1913.)
Sources
- Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).
- Canonical URL: https://worddirectanswers.com/answers/what-is-dioptre-sense-1-called
- Steward: Jason Burns
- Published: 2026-07-17T00:00:00-07:00 · Modified: 2026-07-17T00:00:00-07:00