Source : Webster's Revised Unabridged Dictionary (1913)

Mnemosyne \Mne*mos"y*ne\, n. [L., fr. Gr. ? remembrance, memory,
   and the goddess of memory. See {Mnemonic}.] (Class Myth.)
   The goddess of memory and the mother of the Muses.

Source : WordNet®

Mnemosyne
     n : (Greek mythology) the Titaness who was goddess of memory;
         mother of the Muses