更衣室
gēng yī shì · HSK 7
dressing room
👕🚪 更衣室 = change + clothes + room
更 (change/alter) + 衣 (clothing) + 室 (room) literally stacks to change-clothes-room. By extension covers locker rooms and, as a polite euphemism, the toilet.
更 — 丙 (bǐng) phonetic + 攴/攵 (action/strike)
Originally an oracle-bone graph showing a hand striking a watch-drum to mark night watches, hence 'to change shifts.' From this came the meanings 'to change' and 'to replace' (gēng). The reading gèng later developed the sense 'further, even more,' as in 'one watch further on.'
室 — roof 宀 + arrive 至
A semantic compound: 宀 (roof/house) over 至 (to arrive). The image is a place one arrives at and stays in — an inner room. From 'inner chamber' the meaning broadened to 'room' generally, and by extension to specialized rooms like an office or laboratory.