D defs.my
Entry 1 sense Webster, 1913

Photometer

/fət-äm'-ĭt-ẽr/ · Pho·tom·e·ter · IPA /fəˈtɑmɪtɚ/
01 n. An instrument for measuring the intensity of light, or, more especially, for comparing the relative intensities of different lights, or the…
  1. 1.
    An instrument for measuring the intensity of light, or, more especially, for comparing the relative intensities of different lights, or their relative illuminating power.(Physics)