photometer Syllabification: (pho·tom·e·ter)Pronunciation: /fōˈtämitər/Definition of photometer noun an instrument for measuring the intensity of light. Derivatives photometricPronunciation: /ˌfōtəˈmetrik/ adjective photometricallyPronunciation: /ˌfōtōˈmetrik(ə)lē/ adverb photometryPronunciation: /-ˈtämətrē/ noun photometer in other Oxford dictionaries Definition of photometer in the British & World English dictionary