noun
fervent spirit; intense enthusiasm; burning passion
Describes a state of being fiercely motivated, passionate, or single-mindedly driven. Often used in literary or emphatic contexts.
彼のやたけごころが、ついに難事業を成功させた。
His fervent spirit finally brought the difficult project to success.
やたけごころに燃えて、彼
Burning with intense enthusiasm, she devoted herself to practice every day.