| iodothyronine | (n) thyronine with iodine added |
| triiodothyronine | (n) thyroid hormone similar to thyroxine but with one less iodine atom per molecule and produced in smaller quantity; exerts the same biological effects as thyroxine but is more potent and briefer, Syn. liothyronine, T |
| tri-iodothyronine | (n) thyronine with three iodine atoms added |
| thyroxine | (n) hormone produced by the thyroid glands to regulate metabolism by controlling the rate of oxidation in cells, Syn. tetraiodothyronine, thyroxin, T, Example: thyroxine is 65% iodine |