noun
The eighth planet from the Sun in the Solar System. Used in astronomical contexts.
海王星は太陽系で最も遠い惑星の一つです。
Neptune is one of the farthest planets in the solar system.
Uranus, the seventh planet. Often learned together with Neptune as the outer ice giants.
From 海 (sea) + 王 (king) + 星 (star/planet), a calque of the planet's name Neptune, the Roman god of the sea.