Anuṣṇī (Anushni) is a river mentioned in Padmapurāṇa (Padmapurana).

Padmapurāṇa (Svragakhaṇḍa)(3.21)

Perhaps this very river is known as Anuṣṇā (Anushna) in Mahābhārata (Mahabharata).
[See Anuṣṇā]