noun
waitress (in a ryokan or traditional restaurant); hostess
Refers specifically to a female attendant who serves guests in a traditional Japanese inn (ryokan) or high-end Japanese restaurant, often wearing a kimono and providing attentive service.
旅館の仲居さんが部屋まで料理を運んでくれた。
The ryokan waitress brought the meal to our room.
仲居の仕事は、お客様に気持ちよく過
The job of a nakai is to ensure guests have a pleasant stay.
女中 is a more general term for a maid or female servant, often in a private household, whereas 仲居 is specific to the hospitality industry in traditional inns and restaurants.
Adding さん is a polite and common way to address or refer to a nakai, similar to how one might say 'waitress' versus 'the waitress' in English.
The term 仲居 originally referred to a person who mediated between guests and the establishment, from 仲 (relationship, intermediary) and 居 (being, staying). Over time it became the standard term for a waitress in traditional Japanese inns and restaurants.