tri-iodothyronine
     n : thyronine with three iodine atoms added
Source: WordNet® 2.0

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}]
Source: WordNet® 2.0