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“photoptometer”
photoptometer
A device for testing the acuity of vision by determining the smallest amount of light that will render an object barely visible.
This entry is located in the following units:
meter-, metro-, metr-, -metrical, -metrically, -metron, -metric, -metrist, -meter, -meters, -metry, -metre
(page 31)
photo-, phot-, -photic
(page 13)