鉄てっ心しん

noun

iron core; iron will

Literal meaning: the iron core of an electromagnet or transformer. Figurative meaning: an unyielding, determined spirit.

• この変へん圧あつ器きの鉄てっ心しんは高こう品ひん質しつのケイ素そ鋼こうでできている。

  The iron core of this transformer is made of high-quality silicon steel.

• 彼かれは鉄てっ心しんの持もち主ぬしで、どんな困こん難なんにも負まけない。

  He has an iron will and never gives in to any difficulty.