Main Entry: ac·ti·nom·e·ter

Pronunciation: \ˌak-tə-ˈnäm-ət-ər\

Function: noun

: 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