hot blood; warm blood
Literal meaning referring to blood that is physically warm or hot. Often used in medical or biological contexts.
I felt hot blood circulating through my body.
He's a passionate teacher who's popular with his students.
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).
He is known for his passionate guidance.
That passionate teacher is very popular with the students.
The coach showed his fiery passion during the match.
熱意 describes focused, task-oriented eagerness or earnestness, whereas 熱血 suggests a broader, emotional and spirited disposition.
血気 refers to youthful vigor or rash impulsiveness driven by hot blood, while 熱血 more often carries a positive sense of admirable passion or zeal.
Compound of 熱 (heat) and 血 (blood). The literal meaning 'hot blood' naturally extended to the figurative sense of 'passionate temperament'.