Literal meaning: a massive, immovable rock. Often used in metaphors for stability.
その城は盤石の上に建てられた。
The castle was built on a huge rock.
noun, noun which may take the genitive case particle 'no', na-adjective
firmness; solidity; rock-solid
Figurative use: describes something extremely stable, unshakable, or reliable. Commonly used in phrases like 盤石の体制 (rock-solid system) or 盤石な基盤 (firm foundation).
彼の地位は盤石だ。
His position is rock-solid.
盤石な基盤の上に会社を築く。
Build a company on a firm foundation.
堅固 means 'solid' or 'sturdy' for physical objects or abstract things, but 盤石 carries a stronger image of massive, unbreakable solidity.
large rock; huge boulder · rock-solid; firm; adamant
Standard kanji spelling; used in both literal and figurative senses.
Variant kanji spelling; 磐 also means 'rock' and is interchangeable with 盤 in this word.
From Chinese 盤石 (pánshí), literally 'tray-like rock' or 'massive rock'. The kanji 盤 and 磐 both mean 'large rock' and are used interchangeably in Japanese.