A word in sanskrit denoting a place, or mind set, free of suffering. Free, in fact of ego, percieved and percieved. In contrast to samsara. The hitch is, they are not different. Those interested should check out the likes of Thich Nhat Hanh, Chogyam Trungpa Rinpoche, Pema Chodron, and Tartang Tulku, to node a few.