1911 Encyclopædia Britannica/Sanatorium

SANATORIUM (a modern Latinism, formed from sanare, to cure, restore to health, sanus, whole, healthy, well; often wrongly spelled sanatarium or sanitarium), an establishment where persons suffering from disease, or convalescents, may be received for medical treatment, rest cures and the like; in recent modern usage particularly used for establishments where patients suffering from phthisis may undergo the open-air treatment (see Therapeutics). The mis-spellings of the word, sanitarium and sanatarium, are due to a confusion of “sanatory,” i.e. giving health, from sanare, and “sanitary,” pertaining to health, from sanitas, health.