贵妃 was the second-highest consort rank below 皇后 (empress) during the Tang dynasty. Yang Guifei 杨贵妃 (719–756), beloved of Emperor Xuanzong, is the most famous bearer of the title.
culture
The dish 贵妃鸡 (Guifei chicken) is named after Yang Guifei — it's braised with wine, evoking her reputation for being fond of drink.