"twilled cotton cloth," 1436, from Fr. jean fustian
"fustian (a type of twilled cotton cloth) of Genoa," the city in Italy, from O.Fr. Jannes
"Genoa," from L. Genua,
perhaps from janua
"gate," or in ref. to the god Janus
(q.v.). The plural form became standard 19c. First used 1843 in sense of "pants made from jean."