The true meaning or real essence of something; a profound truth.

(Buddhism) The ultimate or absolute truth, as opposed to conventional truth 世俗谛 shì​sú​dì; often synonymized with 第一义谛 dì​yī​yì​dì

(546-569) A prolific translator of Buddhist texts from India who traveled to China during the Southern and Northern Dynasties, known for introducing Yogachara philosophy.