发病
fā bìng · HSK 6
onset
🤒 发病 = 发 (issue/break out) + 病 (illness) — illness breaks out
发 carries the sense of issuing forth or breaking out (same 发 as 发生 'occur'); 病 is illness. Together: illness issues forth, i.e. the onset or outbreak of disease.
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.'
病 — sickness radical 疒 + 丙 (bǐng, phonetic)
病 is a semantic-phonetic compound. The radical 疒 depicts a person lying on a bed and signals illness or ailment. The component 丙 supplies the sound (bǐng → bìng). Originally 病 referred to a serious illness, contrasted with 疾 for a lighter ailment; today it broadly means 'sick' or 'disease.'