noun \ˌak-tə-ˈnäm-ət-ər\

Definition of ACTINOMETER

: any of various instruments for measuring the intensity of incident radiation; especially : one in which the intensity of radiation is measured by the speed of a photochemical reaction
ac·ti·no·me·tric \-nō-ˈme-trik\ adjective
ac·ti·nom·e·try \-ˈnäm-ə-trē\ noun, plural ac·ti·nom·e·tries

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