"열"

Translation: heat

[LeeQuatorze]

it could also mean a symptom of cold when your forehead becomes hotter than usual and your body temperature rises

[wintertriangles]

AKA a fever

[CF00l]

熱

[soobee620]

"Temper" should be accepted here, especially given the sentence in this lesson (We suddenly lost our tempers = 우리는 갑자기 열을 냈습니다).

Still not accepted two months later (May 2021).

[jinyoungwon]

I wrote “ten" and it was accepted LoL