noun
An older or more literary term for planet; in modern Japanese, 惑星 (わくせい) is far more common. Still seen in some fixed expressions or older texts.
See also: 惑星
遊星という言葉は、今ではほとんど使われない。
The word 遊星 is hardly used nowadays.
古い天文学の本には「遊星」
In old astronomy books, you sometimes see 遊星 written.