Amṛtāṃśūdbhava (Amritamsudbhava) is one of the names of God Viṣṇu (Vishnu), as described in Viṣṇusahasranāmastotra (Vishnusahasranamastotra; Hymn of the Thousand Names of God Vishnu).

Mahābhārata (Kinjawadekar)(13.149.44)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(13.127.44)