noun

1. An utterance of goodbye, the wishing of farewell to someone.

   “They made their good-byes.”

verb

1. To say goodbye; to wish somebody farewell on parting.

interjection

1. Farewell; a formula used to another person or persons when the speaker, writer, or person addressed is departing.

Synonyms: cheerio, cheers, cheery-bye, toodle pip, adieu, farewell, TTFN, bye