a white crystalline nitrogenous substance C4H9N3O2 found especially in the muscles of vertebrates either free or as phosphocreatine; also : a synthetic usually hydrated form of creatine taken especially as a dietary supplement
creatine
noun(cre-a-tine)
any of three isoenzymes found especially in vertebrate skeletal and myocardial muscle that catalyze the transfer of a high-energy phosphate group from phosphocreatine to ADP with the formation of ATP and creatine