noun
hot blood; warm blood
Literal meaning referring to blood that is physically warm or hot. Often used in medical or biological contexts.
熱血が全身を巡る感覚があった。
I felt hot blood circulating through my body.
noun
zeal; fervor; enthusiasm; ardor
Figurative use describing passionate, enthusiastic, or hot-blooded temperament. Often used in compounds like 熱血漢 (passionate person) or 熱血教師 (passionate teacher).
彼は熱血あふれる指導で知られている。
He is known for his passionate guidance.
あの熱血教師は生徒たちに大人気だ。
That passionate teacher is very popular with the students.
Compound of 熱 (heat) and 血 (blood). The literal meaning 'hot blood' naturally extended to the figurative sense of 'passionate temperament'.