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

Mahābhārata (Kinjawadekar)(13.149.90)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(13.127.90)