The term relating to kidneys is 'renal, ' which is a five-letter word. Renal is an adjective that refers to the kidneys, and it is derived from the Latin word for kidney, 'renes.' The kidneys are two bean-shaped organs located in the abdomen that filter waste products from the blood and excrete them in urine. They also help regulate blood pressure, electrolyte balance, and red blood cell production. Renal diseases, such as kidney failure, can be caused by a variety of factors, including genetics, lifestyle, and environmental factors.