Ādirāja(Adiraja) is one of the grandsons of King Kuru and the sons of Avīkṣita (Avikshita).

Mahābhārata (Kinjawadekar)(1.94.52)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(1.89.40)

He is also one among the highly respected kings mentioned in the Anuśāsanaparva (Anusasanaparva) of Mahābhārata (Mahabharata).

Mahābhārata (Kinjawadekar)(13.165.55)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(13.143.52)