From Hindupedia, the Hindu Encyclopedia
By M. A. Alwar
Indrāvarajaḥ is a masculine form.
It is derived from "indrasya avarajaḥ vāmanarūpeṇa anujaḥ" which means 'The younger brother of Indra, as Vāmana'.
Textual reference in Amara
According to Amara he was Lord Viṣṇu. Viṣṇu was born after Indra as Vāmana from Kaśyapa in the womb of Aditi. More details can be seen under the word Vāmana.
- Shabdakalpadrumah by Raja Radhakantdev, Varadaprasada Vasu, Haricarana Vasu