expression, noun-modifying (irregular)
Used prenominally to describe speech, debate, argument, or expression that is filled with strong emotion or intensity. Often implies a positive, earnest passion.
See also: こもる
彼の熱のこもったスピーチに感動した。
I was moved by his passionate speech.
会議では熱のこもった議論が交わされた。
A heated debate took place at the meeting.
熱心 is a noun/adjective meaning 'enthusiasm' or 'eager', describing a person's attitude. 熱のこもった is a prenominal phrase describing the quality of an action or expression as filled with passion.
白熱 means 'incandescence' or 'white-hot', often used for intense debates or competitions. 熱のこもった is less extreme and can describe earnest, heartfelt expression.
Phrase consisting of 熱 (heat, passion) + の (possessive particle) + こもった (past tense of こもる, meaning 'to be filled with'). Literally 'filled with heat', it is used figuratively for passionate expression.