firm and solid; sturdy and indestructible; unshakable
Emphatic expression for something extremely solid, unbreakable, or unwavering. Often used figuratively for resolve, faith, or principles. The term carries a literary or formal tone and is not common in everyday conversation.
His determination is unshakable; no matter what happens, it will not waver.
この城は金剛堅固な造りで、容易には落ちない。
This castle is built so solidly that it will not fall easily.
堅固 means 'solid' or 'firm' and is more common in modern usage. 金剛堅固 is a stronger, more emphatic compound with a literary flavor.
金剛 refers to 'diamond' or 'adamantine' and is often used in Buddhist contexts. 金剛堅固 combines this with 堅固 to intensify the meaning.
A four-character compound (四字熟語) combining 金剛 (diamond, adamantine) and 堅固 (firm, solid). The term originates from Buddhist texts, where it describes the indestructible nature of enlightenment or truth.