Nirvana == 涅槃
Nirvana is a Sanskrit word which is originally translated as "perfect stillness". It has many other meanings, such as liberation, eternal bliss, tranquil extinction, extinction of individual existence, unconditioned, no rebirth, calm joy, etc. It is usually described as transmigration to "extinction", but the meaning given to "extinction" varies.
There are four kinds of Nirvana:
1.Nirvana of pure, clear self-nature
2.Nirvana with residue
3.Nirvana without residue
4.Nirvana of no dwelling