stop number stop net • stop nut · · · Info · Definitions · Synonyms · Characters · · stop number · · Text Common · · Latin · · Scripts 11 · · Length 3 · · Syllables Definitions · · · (noun) the ratio of the focal length to the diameter of a (camera) lens system. Synonyms: focal ratio, f number, stop number, speed. · · Noun Definition 1 Synonyms · · · focal ratio · · Synonym 1 f number · · Synonym 2 speed · · Synonym 3 Characters · · space U+0020 b latin small letter b U+0062 e latin small letter e U+0065 m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074 u latin small letter u U+0075