柯林斯詞典Pluto /?plu?t??/ 1. N the god of the underworld; Hades 冥王[classical myth] Pluto /?plu?t??/ N 1. N the second-largest dwarf planet in the solar system, located in the Kuiper belt; discovered in 1930 by Clyde Tombaugh (1906–97); classified as a planet until 2006, when it was reclassified as a dwarf planet. It has a diameter of 2390 km 冥王星 返回 pluto