Mahāmudrā, the great seal, is the realization that all phenomena are sealed by emptiness and that the mind’s nature is luminous and empty. Drawn from the Indian mahāsiddhas, it is taught especially in the Kagyu and Gelug schools, in both sūtra and tantric forms.
Mahāmudrā
The Great Seal: a Tibetan teaching and practice of recognizing the nature of mind, central to the Kagyu school.
Also: Mahamudra, Great Seal