A gender-neutral term for a person who serves food and drinks in a restaurant or similar setting. Less common than ウェイター/ウェイトレス in casual contexts, but used in formal or written descriptions.
At that restaurant, the waiter carefully brought the dishes to us.
Compound of 給仕 (kyūji, 'serving meals') and 人 (nin, 'person'). The exact historical derivation is uncertain, but the term is conventionally associated with food service roles.