noun
A hollow space inside something, ranging from a small cavity in a wall or tooth to a larger underground cave-like space.
壁の中に小さな空洞があった。
There was a small cavity inside the wall.
調査で地
The survey found a large cavernous hollow underground.
noun which may take the genitive case particle 'no'
hollow; cavernous
Used before の to describe something whose inside is hollow or empty, as in 空洞の pipe, trunk, or structure.
空洞のパイプは見た目より軽い。
A hollow pipe is lighter than it looks.
その古い木は幹の中が空洞の状態だった。
The old tree's trunk was hollow inside.