Etymologically, nirvana (Pali Nibbana) in sutra is "bhavanirodha nibbanam" (The subjugation of becoming means Nirvana). Nirvana in sutra is never concieved of as a place, but the antinomy of samsara which itself is synonymous with ignorance (avijja). “This said: ‘the liberated mind/will (citta) which does not cling’ means Nibbana”[MN2-Att. 4.68]. Nibbana is meant specifically as pertains gnosis which ends the identity of the mind (citta) with empirical phenomena. Doctrinally Nibbana is said of the mind which no "longer is coming (bhava) and going (vibhava)", but which has attained a statis in perpetuity, whereby "liberation (vimutta) can be said".

It carries further connotations of stilling, cooling, and peace; the realizing of nirvana is compared to the ending of avijja (ignorance) which perpetuates the will (citta/mind) from passing through samsara life after life, which causes (and is caused by) among other things craving, consciousness, birth, death, greed, hate, delusion, ignorance. Nirvana, then, is not a place nor a state, it is an absolute truth to be realized, and a person can do so without dying. When a person who has realized nirvana dies, his death is referred as his parinirvana, his fully passing away, as his life was his last link to the cycle of death and rebirth (samsara), and he will not be reborn again. Buddhism holds that the ultimate goal and end of existence is realization of nirvana; what happens to a person after his parinirvana cannot be explained, as it is outside of all conceivable experience.

Gautama Buddha sometimes refers to nirvana as amata ("immortality"). Elsewhere the Buddha calls nirvana 'the unconditioned element' (i.e., that which is not subject to causation). Nirvana is impossible to define directly; it can only be experienced or realized. One may not even be able to say this, since saying this implies the existence of an experiencing subject--which in fact would not persist after full nirvāna. While some of the associated effects of nirvana can be identified, a definition of nirvāna can only be approximated by what it is not. It is not the clinging existence with which man is understood to be afflicted. It is not any sort of becoming. It has no origin or end. It is not made or fabricated. It has no dualities, so that it cannot be described in words. It has no parts that may be distinguished one from another. It is not a subjective state of consciousness. It is not conditioned on or by anything else.

Calling nirvana the "opposite" of samsara or implying that it is apart from samsara is doctrinally inaccurate. They are in fact identical according to early Mahayana Buddhism. Both in early Buddhism and by the time of Nāgārjuna, there are teachings of the identity of nirvana and samsara. However, even here it is assumed that the natural man suffers from at the very least a confusion regarding the nature of samsara.

It should also be noted that the Buddha discouraged certain lines of speculation, including speculation into the state of an enlightened being after death, on the grounds that these were not useful for pursuing enlightenment; thus definitions of nirvāna might be said to be doctrinally unimportant.