Definition - What does Nirvikalpa mean?
Nirvikalpa is a Sanskrit term which can be translated as "transconceptual." The word consists of the prefix nir, meaning "without" or "beyond"; vi, meaning "apart from"; and kalpa, meaning "order." In yoga, it is defined as the processes of the mind that are wordless, with no thought form or discursive thoughts. It is not unconsciousness, but rather awareness that is simple and natural, beyond order, beyond analytical thinking and beyond time, space and knowledge.
Yogapedia explains Nirvikalpa
Nirvikalpa is used in Jnana yoga with samadhi (enlightenment) as nirvikalpa samadhi, which is, according to some sources, the highest form of samadhi. It is enlightenment without thoughts, ideas or form; a state of endless peace and tranquility.
In Shaivism, the term, Nirvikalpa yoga, is used in reference to yoga practice in which there is an experience with the Hindu god, Shiva, as the true Self and total identification with him as an "I" without a form or name.