FLUORESCEIN
fluorescein, fluoresceine, fluorescent dye, resorcinolphthalein
(noun) 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)
Source: WordNet® 3.1
Etymology
Noun
fluorescein (plural fluoresceins)
(chemistry) Any of a class of yellow xanthene dyes which are visible when highly diluted; used forensically to detect traces of blood, and in analytical chemistry as an indicator in silver nitrate titrations
Synonyms
• fluoresceine
• resorcinolphthalein
Source: Wiktionary
Flu`o*res"ce*in, n. (Chem.)
Definition: A yellowish red, crystalline substance, C20H12O5, produced by
heating together phthalic anhydride and resorcin; -- so called, from
the very brilliant yellowish green fluorescence of its alkaline
solutions. It has acid properties, and its salts of the alkalies are
known to the trade under the name of uranin.
Source: Webster’s Unabridged Dictionary 1913 Edition