(1)a dicot family of the order Urticales including: genera Ulmus, Celtis, Planera, Trema
(2)以下を含むイラクサ目の双子葉植物：ニレ、ツェルティス、ニレ属、トレマ
(3)any of various trees of the genus Ulmus: important timber or shade trees
(4)ニレ属の様々な木の総称：重要な材木あるいは緑陰樹