sayonara /ˌsaɪəˈnɑːɹə/exclamation 1noun 1forms 2 exclamation1 •(informal, humorous) Goodbye, adios, adieu.Sonic: Sayonara! Shadow the Hedgehog! — 2001 noun1 •An utterance of sayonara, the wishing of farewell to someone.After a simply marvelous, entertaining two and a half hour meal, they reclaimed their shoes and ceremoniously bid their sayonaras to the Japanese girls. — 1999 formssayonaras · sayōnaras