废寝忘食
fèi qǐn wàng shí · HSK 7
to neglect sleep and forget about food
😴🍽️ 废 waste + 寝 sleep + 忘 forget + 食 food = waste sleep, forget food
Each character spells out the idiom literally: you废 (abandon) your寝 (rest) and忘 (forget) to食 (eat). Used for someone so absorbed in work or study that basic needs fall away entirely.
废 — radical 广 (shelter) + phonetic 发 (fā)
Originally written 廢, this character depicts a building (广, a shelter or house) that has fallen into disuse, with 發 serving as the phonetic component. The core meaning is 'to abandon' or 'discard,' extending to 'ruined,' 'useless,' or 'waste.' The simplified form 废 replaces 發 with 发.
忘 — 亡 (lose/perish) on top + 心 (heart) on bottom
忘 is a semantic-phonetic compound. The bottom 心 (heart/mind) gives the meaning, since forgetting happens in the mind, while the top 亡 (to lose, perish) supplies both the sound and the sense of something gone. Together they depict a thought lost from the heart — to forget.