see jean.
"twilled cotton cloth," mid-15c., from Middle French jean fustian "fustian (a type of twilled cotton cloth) of Genoa," the city in Italy, from Old French Jannes "Genoa," from Latin Genua (see Genoa). The plural form jeans became standard 19c.
trousers originally designed in the United States by Levi Strauss in the mid-19th century as durable work clothes, with the seams and other points of stress reinforced with small copper rivets. They were eventually adopted by workingmen throughout the United States and then worldwide.