n. [ Pref. astro- + photometer. ] (Astron.) A photometer for measuring the brightness of stars. [ Webster 1913 Suppl. ]
n. [ Photo- + -meter: cf. F. photomètre. ] (Physics) An instrument for measuring the intensity of light, or, more especially, for comparing the relative intensities of different lights, or their relative illuminating power. [ 1913 Webster ]
n. [ Spectrum + photometer. ]