In Hinduism, Nirvichara Samadhi is a conceptual term relating to Yoga. Samadhi is defined by Patanjali as a state of the citta (internal organ) having two qualities -
Experiencing only the object of contemplating exclusively (arthamatranirbhasata) and absence of self awareness (svarupasunyata) (Yogasutra – III; 3). It arises out of the state of dhyana, which itself is an extension of the state of dharana. The three states together constitute what is called antaranga (internal Yoga).
There are two main varieties of Samadhi respectively called sabija Samadhi (Samadhi with seed) and nirbija Samadhi (Samadhi without seed). Seed here means the object of contemplation.
Nirbija Samadhi is also called sahajvastha, jivanmukti or asamprajnyata yoga, i.e., asamprajnyata Samadhi. Sabija Samadhi is also called samprajnyata Samadhi, salambana Samadhi, or samapatti. It has four varieties, respectively called savitaraka, nirvitarka, savihara, and nirvicara (Yoga Sutra – I : 42 – 46). The first two together constitute vitarka samapatti which has sthula alambana (gross object of concentration). The last two together constitute vicara samapatti, which has a sukshma alambana (subtle object of contemplation). Nirvichara Samadhi is the highest among the four.
The two qualities of Samadhi mentioned above (Yogasutra – III : 3), namely, totally, experiencing of the object alone, and absence of self awareness, are found in both nirvitarka and nirvichara varieties of Samadhi. They differ only in respect of grossness and subtleness of the object of contemplation.
By expertise in the nirvichara state of Samadhi, an adept achieves adhyatma-prasada (undisturbed calm) (Yoga Sutra – I: 47). That leads to ritambhara prajna (unfailing intellect) (I:48). It yields self knowledge which lies beyond the scope of the ordinary intellect. By that the adept becomes a jivanmukta, i.e., one who is liberated in bodily existence.