Source : Webster's Revised Unabridged Dictionary (1913)

Iodothyrin \I`o*do*thy"rin\, n. [Iodo- + thyro- + -in.]
   (Physiol. Chem.)
   A peculiar substance obtained from the thyroid gland,
   containing from nine to ten per cent of iodine.

   Note: It is a very stable compound, and is believed to be
         active principle in thyroid extracts and in the
         internal secretion of the thyroid gland. It was
         originally called {thyroiodin}.