noun
luminous moss
A type of moss known for its bioluminescent or light-reflecting properties. Often used in literary or poetic contexts.
洞窟の中で光蘚が青白く輝いていた。
The luminous moss glowed pale blue inside the cave.
Compound of 光 (hikari, 'light') and 蘚 (koke, 'moss'). The exact derivation is uncertain; the spelling is conventionally associated with the meaning.