diopter
di·op·ter
noun \dī-ˈäp-tər, ˈdī-ˌäp-\Definition of DIOPTER
: a unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length in meters
Origin of DIOPTER
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
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