Proper noun
(Greek mythology) One of the Charites; she is the goddess and personification of relaxation, meditation and hallucinations. She is the wife of Hypnos and the mother of the Oneiroi.
(Greek mythology) One of the Nereids.
Source: en.wiktionary.orgHypnos made her swear by the river Styx and call on gods of the underworld to be witnesses so that he would be ensured that he would marry Pasithea. Source: Internet