The story
Haplology from Latin sanatus (past participle of sānō (“to cure, to heal”)) + Latin -torium. Alternatively, alteration of sanitarium influenced by words like curatorium and moratorium.
Etymology from Wiktionary, CC BY-SA 4.0.
sanatorium
san·a·to·ri·umToday it means: An institution that treats chronic diseases, and provides supervised recuperation and convalescence. Full definition →