noun
Refers to a hollow space inside something, such as a tree hollow, a cavity in a rock, or an empty space. Often used in descriptive or literary contexts.
古い木の幹に大きなうろができていた。
A large hollow had formed in the trunk of the old tree.
岩のうろに小さな蟹が隠れている。
A small crab is hiding in a cavity in the rock.
Kana spelling, sometimes used when the kanji is not needed.
Rare kanji variant for 'hollow' or 'cavity'.
Alternate kanji spelling, also used for 'hollow'.
The origin is uncertain, but it may be related to the idea of emptiness or hollowness. The kanji 虚 and 空 both carry meanings of 'void' or 'empty', while 洞 means 'cave' or 'hollow'.