noun
heat; thermal energy
Physical heat, as in temperature, cooking, or physics.
夏の暑さで熱がこもる。
Heat builds up in the summer heat.
熱を加えると溶ける。
It melts when heat is applied.
noun
fever; high temperature
Body temperature above normal; often used with ある, 出る, 下がる, etc.
熱があるので、今日は休みます。
I have a fever, so I'll take the day off.
子供の熱が下がらない。
The child's fever won't go down.
noun, suffix
zeal; passion; enthusiasm; craze
Intense emotional energy or enthusiasm; also used as a suffix for fads or obsessions (e.g., 〇〇熱).
彼は仕事に熱を入れている。
He puts passion into his work.
最近、キャンプ熱がすごい。
Lately, the camping craze is intense.