Old Surgery Aid is a term that refers to ETHER, a five-letter substance used in medical procedures. ETHER was first used as an anesthetic in the early 19th century and has been used in surgery ever since. It is a colorless, volatile liquid with a sweet odor and taste, and it has a wide range of medical applications, including as an anesthetic, sedative, and antiseptic. ETHER is also used in some industrial processes, such as in the production of plastics and rubber.