To secretly hide a profound mystery, deep principle, or hidden agenda; to contain a hidden catch or underlying complexity.

a mysterious and ingenious plan; to have divine foresight or highly brilliant schemes

(c. 844–871) Renowned poet of the late Tang Dynasty, born in Chang'an; originally named [[鱼幼微|魚幼微|yu2 you4 wei1]], she was briefly a concubine before becoming a Daoist nun at the Xianyiguan convent and was eventually executed for the death of her maid.