鉄てっ心しん石せき腸ちょう

Meanings

1

noun

will of iron; iron will; unyielding spirit

yojijukugo (four-character idiom)

A yojijukugo describing an extremely firm, unshakable will, like iron and stone. Literary and somewhat emphatic.

彼かれは鉄てっ心しん石せき腸ちょうの持もち主ぬしで、どんな困こん難なんにも屈くっしない。
He has an iron will and never gives in to any hardship.

intestines, guts, bowels

Similar words

鉄てつの意い志し
More common, straightforward phrase for 'iron will'. 鉄心石腸 is a more literary, four-character idiom.
不ふ撓とう不ふ屈くつ
Another yojijukugo meaning 'indomitable' or 'unyielding', but focuses on not bending or giving up, while 鉄心石腸 emphasizes the hardness of the will itself.

Etymology

A yojijukugo composed of 鉄 (iron) + 心 (heart/mind) + 石 (stone) + 腸 (guts/intestines, metaphorically the seat of emotions). The combination suggests a mind and spirit as hard as iron and stone. The exact origin is uncertain, but it follows a common pattern of pairing hard materials with inner qualities.