lour(also lower), / ˈlauə(r); laʊr/ v [I, Ipr]~ (at/on sb/sth)(a) look threatening; frown 作怒相; 皱眉 louring looks 怫然不悦的神情.(b) (of the sky, clouds, etc) look dark, as if threatening a storm （指天气、 云等）变阴暗（似预示暴风雨）.
牛津英汉双解词典