*plan·et/`plænɪt; ˈplænɪt/ n [C] 1 a very large round object in space that moves around a star such as the sun 行星: Pluto is the smallest planet. 冥王星是最小的行星。 the planet Earth 地球 2 the planet the world 全球，全世界: the environmental future of the planet 全球环境的未来