城
しろ · shiro · JLPT N3 · noun
palace
🏯 城 = earth 土 + become 成: earth built up into a castle
The left side 土 means earth; the right side 成 means to become or complete. Packed earth made into walls becomes a castle. Sound hook: shiro also means white (白), and Himeji, the most famous shiro, is the white castle.
城 — earth radical 土 + 成 (to complete)
Originally a semantic-phonetic compound: 土 (earth) gives the meaning, since ancient cities were defended by rammed-earth walls, while 成 supplies the sound. The earliest meaning was 'city wall,' which later broadened to 'walled city' and then simply 'city' or 'town.'