\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}.