diuretic

as an adjective, "inducing or promoting urination;" as a noun, "medicine that promotes urination;" c. 1400 diuretik (adjective and noun), from Old French diuretique, from Late Latin diureticus, from Greek diouretikos "prompting urine," from diourein "urinate," from dia "through" (see dia-) + ourein "urinate," from ouron (see urine).