发热
fā rè · HSK 7
to have a high temperature
🤒🔥 发 (emit/send out) + 热 (heat) = sending out heat, running a fever
The literal breakdown is straightforward: 发 means to emit or release, 热 means heat. Together they describe the body releasing excess heat — a fever. The figurative sense extends to being hot-headed, unable to think calmly.
发 — simplified form of 發; from 癶 (two feet) + 弓 (bow) + 殳 (weapon)
The traditional form 發 depicted shooting an arrow from a bow, with 癶 showing outstretched feet and 弓 the bow, giving the core sense of 'send out, discharge.' From this came extended meanings like 'issue, emit, develop.' The modern simplified 发 also absorbed 髮 (hair), so it now covers both 'to send out' and 'hair.'
热 — 执 zhí (phonetic) + 灬 fire radical
热 is a semantic-phonetic compound: the bottom 灬 (a variant of 火 'fire') gives the meaning of heat, while 执 on top supplies the sound. Originally written 熱, it depicted fire below a phonetic element, and the meaning naturally extended from physical heat to 'hot' weather and 'enthusiastic' feelings.