Source : Webster's Revised Unabridged Dictionary (1913)

Isatin \I"sa*tin\, n. [See {Isatis}.] (Chem.)
   An orange-red crystalline substance, {C8H5NO2}, obtained by
   the oxidation of indigo blue. It is also produced from
   certain derivatives of benzoic acid, and is one important
   source of artificial indigo. [Written also, less properly,
   {isatine}.]