金きん城じょう鉄てっ壁ぺき

noun

impregnable castle walls

Literal meaning of the yojijukugo, referring to fortress walls that cannot be breached.

• 金きん城じょう鉄てっ壁ぺきの城しろは、どんな攻こう撃げきにも耐たえた。

  The castle with impregnable walls withstood any attack.

noun which may take the genitive case particle 'no'

impregnable; invulnerable; unassailable

Figurative use describing something extremely secure or impossible to defeat, such as a defense, argument, or system.

• 彼かれの論ろん理りは金きん城じょう鉄てっ壁ぺきで、反はん論ろんの余よ地ちがなかった。

  His logic was unassailable, leaving no room for counterargument.

• 金きん城じょう鉄てっ壁ぺきの守しゅ備び陣じんが相あい手ての攻こう撃げきを封ふうじた。

  The impregnable defense shut down the opponent's attacks.