an orange-red crystalline compound that in aqueous solution exhibits a greenish-yellow fluorescence in reflected light and is reddish-orange in transmitted light: used as a marker in sea water and as an indicator. Formula: C20H12O5
(fl-rěs'ē-ĭn, flô-) An orange-red crystalline compound that exhibits intense fluorescence in alkaline solution. It is used in medicine for diagnostic purposes, in oceanography as a tracer, and as a textile dye. Chemical formula:C20H12O5.