Word Study
bye-bye
WORDNET DICTIONARY
Noun bye-bye has 1 sense
- bye-bye(n = noun.communication) adieu, adios, arrivederci, au revoir, auf wiedersehen, bye, cheerio, good day, good-by, good-bye, goodby, goodbye, sayonara, so long - a farewell remark; "they said their good-byes" is a kind of farewell, word of farewell
OXFORD DICTIONARY
bye-bye, int. colloq. = GOODBYE.
bye-bye, n. (also bye-byes) (a child's word for) sleep.
Etymology
ME, f. the sound used in lullabies
For further exploring for "bye-bye" in Webster Dictionary Online
