熱い means hot to the touch, 暑い means hot weather or surroundings, and 厚い means thick. Use 熱い for hot tea or a heated surface, 暑い for a hot day or room, and 厚い for a thick book. Their common opposites—冷たい, 寒い, and 薄い—are a useful check, though each word has further figurative uses.
also written atsui / 熱い / 暑い / 厚い / 篤い
熱い — hot to the touch · 暑い — hot weather · 厚い — thick
Sentences
6 sentences, word by word
熱い — you could burn yourself
polite
、。
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気
き ［0］
care; attention
noun · 気をつける is the set phrase for taking care
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を
を
marks the direct object
particle · pronounced お
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つけて
つけて
attach; take (care)
て-form of つける · used alone as a warning
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お茶
おちゃ ［0］
tea
noun · the お is fixed in this word
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が
が
marks the subject
particle · what the sentence is about — with 好き, 分かる and potentials, the object
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熱い
あつい ［2］
hot to the touch
い-adjective · the opposite is 冷たい, which settles the kanji
熱いN5hot · to the touch
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です
です
(polite ending)
copula · politeness on an い-adjective predicate
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Careful, the tea is hot.
暑い — the air around you
plain
。
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今日
きょう ［1］
today
noun used adverbially · relative time, no particle
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は
は
as for — the topic
particle · written は, read わ
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本当に
ほんとうに ［5］
really
adverb · intensifying what follows
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暑い
あつい ［2］
hot (weather)
い-adjective · the opposite is 寒い, so this is the weather one
暑いN5hot · weather
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ね
ね
isn't it
sentence particle · inviting agreement
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It's really hot today.
厚い — thickness, not heat
polite
。
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それ
それ
that
pronoun · the object near the listener
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は
は
as for — the topic
particle · written は, read わ
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とても
とても
very
adverb · intensifying the adjective
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厚い
あつい ［0］
thick
い-adjective · the opposite is 薄い — nothing to do with heat
厚いN5thick
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本
ほん ［1］
book
noun · the thing being measured
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です
です
(polite ending)
copula · the polite assertion
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That's a very thick book.
熱い — a hot bath on a hot day
plain past
、。
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暑い
あつい ［2］
hot (weather)
い-adjective · describing the day, so the weather kanji
暑いN5hot · weather
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日
ひ ［0］
day
noun · the day being described, which is why 暑い and not 熱い
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な
な
(attributive)
copula な · a noun before のに takes な, never だ — 日なのに
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のに
のに
even though
conjunction · the contrast between the two kinds of heat
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お風呂
おふろ ［2］
bath
noun · an object you get into, so 熱い
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が
が
marks the subject
particle · what the sentence is about — with 好き, 分かる and potentials, the object
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熱すぎた
あつすぎた
was too hot
熱い ＋ すぎる in past · excess of touchable heat
熱いN5hot · to the touch
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The bath was too hot, even though it was a hot day.
厚い — figurative depth
polite
。
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彼
かれ ［1］
he
pronoun · the person trusted
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は
は
as for — the topic
particle · written は, read わ
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チーム
チーム
team
noun · loanword, always katakana
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の
の
links noun to noun
particle · A の B = B belonging to A
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厚い
あつい ［0］
deep; strong
い-adjective · figurative thickness, not heat
厚いN5thick · deep
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信頼
しんらい ［0］
trust
noun · 信頼を得る, to earn trust
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を
を
marks the direct object
particle · pronounced お
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得て
えて
has earned
て-form of 得る · linking into います
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います
います
is (doing)
polite of いる · marks an ongoing state
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He has the team's deep trust.
熱 — the noun behind 熱い
plain
。
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熱
ねつ ［2］
fever; heat
noun · 熱がある is the set phrase for running a temperature
熱があるN5have a fever
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が
が
marks the subject
particle · what the sentence is about — with 好き, 分かる and potentials, the object
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ある
ある
there is; I have
plain ある · possession of a condition
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みたい
みたい
it seems
conjecture · from what the speaker can feel
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だ
だ
is
plain copula · みたい behaves as a な-adjective
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I think I've got a fever.
Structure
Which one goes with what
お茶 / お風呂 / 鉄＋が熱い
お茶が熱い. Also figurative heat: 熱い思い, passionate feeling; 熱い試合, a fiercely fought match.
今日 / 夏 / 部屋＋が暑い
今日は暑い. Never about an object — a hot cup of tea is 熱い, even on a 暑い day.
本 / コート / 壁＋が厚い
厚い本. Figuratively 厚い信頼, deep trust — depth rather than heat.
熱い↔冷たい·暑い↔寒い·厚い↔薄い
Say the opposite out loud. Only one of the three will make sense, and that settles the kanji.
Meaning
The antonym test, and where each one goes figurative
Touchable heat is 熱い. Tea, a bath, a pan, a forehead. If you could burn yourself on it, this is the one — and its opposite is 冷たい, cold to the touch.
Air is 暑い. The day, the room, the summer. It describes the environment you are standing in, never an object in it. Its opposite is 寒い, and the pairing is exact: you would never call a cold drink 寒い.
厚い is not about temperature. It means thick — a book, a coat, a wall, a slice of toast. Its opposite is 薄い, and its meaning is distinct from temperature.
Figurative uses depend on the word.熱い思い expresses passion, and 厚い信頼 expresses deep trust. 暑い chiefly describes environmental heat; avoid assuming that a shared pronunciation gives these words the same figurative uses.
The related words split too.熱がある means running a fever, from 熱 heat. 暑がり is somebody who feels the heat, and 厚さ is thickness as a measurement.
Watch out
Where the three あつい go wrong
暑いお茶
Tea is an object you could touch, so it is 熱いお茶. 暑い only ever describes the air around you.
熱い日
A day is weather: 暑い日. 熱い on a day would suggest the day itself could burn you.
Assuming 厚い belongs with the other two
厚い has no temperature sense. Its usual opposite is 薄い. The words share a reading, but their meanings differ.
Also asked
Questions people ask about あつい
How do I remember which is which?
Say the opposite. 冷たい gives you 熱い, 寒い gives you 暑い, 薄い gives you 厚い. Only one will fit.
Do the kanji help?
Partly. 熱 has the fire radical 灬 along the bottom, and that one is reliable. 日 does not separate the other two — 暑 has the sun on top, but 厚 contains a 日 as well, under the cliff radical 厂. For those two the antonym is the surer test.
What is 熱い試合?
A fiercely contested match. 熱い extends naturally to passion and intensity — 熱い思い, 熱く語る.
Can 暑い be figurative?
暑い chiefly describes weather or ambient heat. It has expressive uses in context, so “never figurative” is too strong.
What about 篤い?
Devoted or earnest, and rare. You will meet it in set phrases like 篤い信仰. Recognise it in reading; there is no need to produce it.
Is 熱 the same word as 熱い?
Same character, different word. 熱 read ねつ is a noun — heat, or a fever. 熱がある is the standard way to say you are running a temperature.
