Creatinin \Cre*at"i*nin\ (kr?-?t"?-n?n), n. (Physiol. Chem.)
A white, crystalline, nitrogenous body closely related to
creatin but more basic in its properties, formed from the
latter by the action of acids, and occurring naturally in
muscle tissue and in urine. [Written also {kretinine}.]
[1913 Webster]