The term 'anesthetic, formerly' can be summarized by the crossword solution 'ETHER'. ETHER was a type of anesthetic used in the 19th century to induce unconsciousness during surgery. It was discovered in 1846 by American physician and chemist Dr. William T. G. Morton and was the first anesthetic to be used in a successful public demonstration of surgical anesthesia. ETHER was widely used until the mid-20th century when it was replaced by safer and more effective anesthetics.