The term 'PERTAINING TO KIDNEYS' can be summarized by the word 'RENAL', which is a five-letter word. Renal is an adjective that describes something related to the kidneys, such as renal failure or renal disease. The kidneys are two bean-shaped organs located in the abdomen that filter waste from the blood and excrete it in the form of urine. They also help regulate blood pressure, electrolyte balance, and red blood cell production.