金きん城じょう湯とう池ち

noun

impregnable fortress; unassailable stronghold

Figurative yojijukugo describing a position, argument, or territory so well-defended that it cannot be breached. Often used in political, business, or debate contexts.

• 彼かれの理り論ろんは金きん城じょう湯とう池ちのごとく、誰だれも反はん論ろんできなかった。

  His theory was like an impregnable fortress; no one could argue against it.