mahāmudrā

(Sanskrit)
1. Great Seal; one of the four meditational seals (mudrā) according to yoga-tantra. It refers to the process of imaging the Buddhas in transformational meditation practice by way of their body-images (bimba) which correlate to their body aspect (see body, speech, mind).

2. A category of practices and their associated goal, especially linked with anuttara-yoga-tantra, although there are two aspects to the practice: the sūtra-based ‘ordinary’ form and the tantra-based ‘extra-ordinary’ form. In both cases, the aim of the practice is to realize the emptiness (śūnyatā) of all phenomena, their intrinsic luminosity and the inseparable union of these two aspects. A major form of tantric Buddhist teaching and practice, mahāmudrā was transmitted to Tibet by Marpa who received it from the mahā-siddha (‘great adept’) Nāropa. From Marpa, the teachings went to Milarepa, and from him to Gampopa. Through the efforts of the latter, mahāmudrā became one of the core elements of the Kagyü school. The central element of mahāmudrā teaching involves a recognition of the inseparable nature of compassion (karuṇā) and insight (prajñā) or the identity of emptiness (śūnyatā) and saṃsāra.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)

【梵】महामुद्रा【中】大姥達羅
【藏】rgya rtags chen po
【藏】རྒྱ་རྟགས་ཆེན་པོ་

Mahāvyutpatti - DDBC version