Polite noun for changing clothes, often used in service contexts or formal situations. The verb form is 召し替える.
Please use this room when you change your clothes, sir/madam.
After arriving at the inn, I first changed my clothes.
Standard kanji spelling using 替 (replace).
Variant using 換 (exchange); less common but attested.
Compound of 召し (honorific prefix from 召す, 'to wear') and 替え (from 替える, 'to change').