Source : WordNet®

fluoresceine
     n : a yellow dye that is visible even when highly diluted; used
         as an absorption indicator when silver nitrate solution
         is added to sodium chloride in order to precipitate
         silver chloride (turns pink when no chloride ions are
         left in solution and negative fluorescein ions are then
         absorbed) [syn: {fluorescein}, {fluorescent dye}, {resorcinolphthalein}]