Shunyata (Tib. stong-pa-nyid, Chin. kung),usually translated as "emptiness", "voidness", "nothingness", or even "relativity", is a key technical and philosophical term in the Mahayana Buddhist tradition.
This is a difficult term, usually translated as "Void" or "Emptiness", but sometimes more positively as "Openness". The philosophical nuances of this term are complex. Emptiness must not be understood as simple nihilism (the denial that anything exists), much less as referring to some absolute entity that underlies appearance. Rather, things are "empty" in the sense of lacking independent, persistent existence.
In the Buddhist scholar H. V. Guenther's words: "the technical term shunya indicates the "open dimension of being". The customary translations by "void" or "emptiness", fail to convey the positive content of the Buddhist idea" .
While according to T. R. V. Murti , the terms shunya and shunyata are used in two allied meanings.
For an in-depth philosophical discussion, see Francis Streng, Emptiness: A Study in Religious Meaning (Abingdon Press, 1975) (unfortunately out of print).
Ultimately shunyata is a phenomenological term for the experience of the Absolute Reality. The Absolute Reality is the experience of total freedom from the distortion and limitations of conceptual understanding (vikalpa), it is "empty" or "void" of all such particular characteristics. This Shunyata, according to the great 2nd Century Buddhist dialectician Nagarjuna, can only be described in terms of a paradoxical series of negations. So for example in Absolute Reality (Shunyata) there is neither Movement nor non-Movement nor both Movement and non-Movement nor something other than Movement and non-Movement. Reality embraces all, includes all and transcends all.
 T. R. V. Murti, The Central Philosophy of Buddhism, p.349 (Unwin Paperbacks, London 1955/1980)