NOUN (1)

1. (Greek mythology) the Titaness who was goddess of memory; mother of the Muses;

The Collaborative International Dictionary of English v.0.48:

Mnemosyne \Mne*mos"y*ne\, n. [L., fr. Gr. mnhmosy`nh
   remembrance, memory, and the goddess of memory. See
   Mnemonic.] (Class Myth.)
   The goddess of memory and the mother of the Muses.
   [1913 Webster]