熱い|あついatsui[2]nakadaka (mid-high)

1. i-adjectivehot (to the touch)
   スープは熱あついうちに召し上めしあがって下ください。↗

   Eat your soup while it is hot.
2. i-adjectivepassionate (feelings, etc.); ardent; hot (e.g. gaze)
3. i-adjectivehot (e.g. temper)
4. i-adjectivezealous; enthusiastic; fired up
5. i-adjectiveintense; severe; extreme
6. i-adjectivehot (topic); of interest

• SynonymホットCasualColloquial loanword for hot drinks or hot topics, as in 「ホットコーヒー」 and 「ホットな話題」; for things hot to the touch, 「熱い」 is the everyday word.
• Synonym熱っぽいねつっぽいNeutralSlightly feverish, or speech and attitude tinged with enthusiasm; unlike 「熱い」 it never describes hot objects.
• Related暖かいあたたかいNeutralWarm rather than hot: a moderate, comfortable temperature, a lower degree than 「熱い」, and generally a pleasant sensation.
• Related暑いあついNeutralFor hot weather and high air temperature; 「熱い」 is for hot objects and ardent feelings instead.
• Related熱烈ねつれつWrittenWritten/formal: fervent, ardent feelings or attitudes, as in 「熱烈な歓迎」; not used for hot objects.
• Related熱心ねっしんNeutralEarnest and devoted to what one does, as in 「熱心に勉強する」; about diligence, not heat or burning emotion.
• Related温暖おんだんWrittenWritten/formal word for a mild, pleasant climate, used of a region's weather; never for hot objects.
• Related生暖かいなまあたたかいNeutralLukewarm — neither cold nor hot, with an unpleasant feel; it points the opposite way from scalding 「熱い」.
• Related暖かあたたかWrittenNa-adjective form of 「暖かい」, usually as 「暖かな」, with a written flavor; stresses comfortable warmth rather than heat.
• RelatedぬくいCasualColloquial, in Kansai and other dialects, for pleasant warmth; it never refers to scalding heat like 「熱い」.
• Related情熱的じょうねつてきNeutralBurning with passion for something, as in 「情熱的なダンス」; describes people and their manner, not hot objects.
• Related熱情的ねつじょうてきNeutralBlazing, intense emotion; slightly more written/formal than 「情熱的」.
• Related熱狂的ねっきょうてきNeutralFrenzied enthusiasm, as in 「熱狂的なファン」, implying a loss of composure; much stronger than the passion of 「熱い」.
• Related白熱的はくねつてきWrittenWritten/formal, for contests or discussions at white heat, as in 「白熱的な議論」; fairly rare.
• Antonym冷たいつめたいNeutralThe opposite of 「熱い」: icy-cold objects, and by extension a cold, unfriendly attitude toward people.

Default to 「熱い」 for hot objects and ardent feelings — even 「熱いお茶」. Use 「暑い」 for hot weather, 「暖かい」 for comfortable warmth, 「熱心」 for earnest effort, 「熱狂的」 for frenzy, 「ホット」 for drink names, and 「冷たい」 for icy cold.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. その物ものの温度おんどがかなり高たかい。また、対象物たいしょうぶつが強つよく熱ねつを帯おびている。
2. 情熱的じょうねつてきだ。熱心ねっしんだ。
3. 男女だんじょの仲なかが、目めだってよい。
4. 人気にんきの。注目ちゅうもくされている。