留める
とめる · tomeru · JLPT N3 · verb-ichidan
to fasten
📌 留 = stay (留学, 留守); 留める = make it stay: pin, fasten, detain
留 means remain or stay, so 留める is to keep something in place: pin a note, fasten a button, hold someone back. It is also read とめる, like 止める (stop, turn off), and that word is usually the one used for switching things off.
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).