name given to various chronic skin diseases, later in more restricted use, 1530s, probably from leprous + -y (4). First used in Coverdale Bible, where it renders Hebrew cara'ath, which apparently was a comprehensive term for skin diseases. Because of pejorative associations, the use of the word in medical context has been banned by the World Health Organization and replaced by Hansen's disease (1938), named for Norwegian physician Gerhard Henrik Armauer Hansen (1841-1912) who in 1871 discovered the bacillus that causes it.
The Middle English name for the disease was leper (mid-13c.), from Old French liepre and Latin lepra (see leper). But as the sense of this shifted after late 14c. to mean "person with leprosy," English began coining new nouns for the disease: lepri, leprosity, lepruse all date from mid-15c. but are now obsolete. A place for their treatment is a leprosarium (1846) or leprosary (1869, from French).