"leprous" (adj.); "a leper" (n.); both c.1300, from Old French mesel "wretched, leprous; a wretch," from Latin misellus "wretched, unfortunate," as a noun, "a wretch," in Medieval Latin, "a leper," diminutive of miser "wretched, unfortunate, miserable" (see miser). Also from Latin misellus are Old Italian misello "sick, leprous," Catalan mesell "sick."