扣留
koù liú · HSK 7
to detain
🔒👮 扣 fasten/hold + 留 keep/stay = hold someone and make them stay = detain
扣 (koù) means to fasten or hold back; 留 (liú) means to keep or stay. Hold a person back and force them to stay = to detain, arrest, or confiscate. Sound hook: koù-liú, the kou clamps and the liu lingers.
扣 — hand radical 扌 + 口 (mouth/phonetic)
扣 is a phono-semantic compound: the hand radical 扌 signals an action done with the hand, while 口 (kǒu) supplies the sound. Its core sense is to knock, fasten, or buckle with the hand, later extending to deduct (as in deducting points) and to button up.
留 — 卯 (top) + 田 (field)
Originally a phono-semantic compound: 田 (field) suggests staying on the land, with 卯 hinting at the sound. Over time it came to mean 'remain, stay, keep,' as in keeping someone on the land or holding something in place. Modern uses include 留学 (study abroad) and 保留 (retain).