One of the names of Śiva-Mahādeva (Siva-Mahadeva), described in Śivasahasranāma (Sivasahasranama; thousand names of Siva). Nīlakaṇṭha (Nilakantha), the commentator, has analysed the meaning of the name in the following way:
ātmani jīve niścitya dehādupādhevā
nirgatya ālocayatīti atmanirālokaḥ.
In Sanskrit, the śabda (sabda; word) āloka (aloka; light) derives from ‘loc’ dhātu (dhatu; the root of a verb), which means ‘to have a vision’ or ‘to get revealed’. Mahādeva (Mahadeva) Himself is nirākāra Paramātman (nirakara Paramatman; the formless, absolute Self); He cannot be visualised. But as Parabrahman, He manifests himself as the Jīvātmā (Jivatma; the soul of living beings) present in all living beings. The Paramātman can be seen through the Jīvātmā manifested in all creatures — from this concept, Mahādeva has been called Ātmanirāloka (Atmaniraloka).