triiodothyronine
noun
tri·io·do·thy·ro·nine ˌtrī-ˌī-ə-dō-ˈthī-rə-ˌnēn 
: an iodine-containing hormone C15H12I3NO4 that is an amino acid derived from thyroxine
called also T3
Example Sentences
Recent Examples on the Web The hormones that the thyroid gland makes — triiodothyronine, or T3, and thyroxine, or T4 — affect all aspects of your metabolism. 
Mayo Clinic News Network, chicagotribune.com, 4 Oct. 2019 Your thyroid produces hormones like thyroxine and triiodothyronine, which influence many of your body’s systems, according to the Mayo Clinic. Zahra Barnes, SELF, 16 Jan. 2018
Mayo Clinic News Network, chicagotribune.com, 4 Oct. 2019 Your thyroid produces hormones like thyroxine and triiodothyronine, which influence many of your body’s systems, according to the Mayo Clinic. Zahra Barnes, SELF, 16 Jan. 2018 Word History
Etymology
tri- + iod- + thyronine an amino acid of which thyroxine is a derivative
First Known Use
1952, in the meaning defined above
Medical Definition
triiodothyronine
noun
tri·io·do·thy·ro·nine ˌtrī-ˌī-əd-ō-ˈthī-rə-ˌnēn
: a crystalline iodine-containing hormone C15H12I3NO4 that is an amino acid derived from thyroxine and is used especially in the form of its soluble sodium salt C15H11I3NNaO4 in the treatment of hypothyroidism and metabolic insufficiency
called also liothyronine, T3