Bye-bye and Bye-byes

Bye-bye noun - A farewell remark.

Bye-byes and bye-bye are semantically related In some cases you can use "Bye-byes" instead the phrase "Bye-bye" as a noun or a interjection.

Bye-bye and bye-byes are semantically related in departure topic. You can use "Bye-bye" instead the phrase "Bye-byes" as a interjection or a noun, if it concerns topics such as goodbye, farewell statement, have a nice trip.