is a combination of the Greek a-,designating "absence or failure," + chalasis, "relaxation," and we use the word in its lit eral sense, "a failure of relaxation." The con dition known as achalasia is most often found in the esophagus, where it is specifically a failure in relaxation of the LES (Lower Esophageal Sphincter) muscle, as distinguished from dif fuse Esophageal Spasm. There is a nice dis tinction between achalasia and spasm, the difference being immediately clear to one who knows the derivation of "achalasia."