noun Ur·bain Jean Jo·seph [yr-ban zhahn zhaw-zef] /ürˈbɛ̃ ʒɑ̃ ʒɔˈzɛf/, 1811–77, French astronomer. nounUrbain Jean Joseph (yrbɛ̃ ʒɑ̃ ʒozɛf). 1811–77, French astronomer: calculated the existence and position of the planet Neptune