What does Nitya mean?
From Sanskrit nitya (नित्य), 'eternal, perpetual, constant'; also used as an epithet of the Goddess (Durga/Devi). Well established.
What does Vaishnavi mean?
From the Sanskrit वैष्णवी (vaiṣṇavī), feminine of Vaishnava, 'relating to Vishnu'. It denotes a female devotee of Vishnu and is also the name of the Shakti (divine energy) of Vishnu, one of the Sapta Matrikas.