Bye-bye and Swan song

Bye-bye noun - A farewell remark.

Swan song and bye-bye are semantically related. in farewell statement topic. In some cases you can use "Swan song" instead a noun phrase "Bye-bye".

Swan song noun - A final performance or effort (especially before retirement).

Bye-bye and swan song are semantically related. Sometimes you can use "Bye-bye" instead a noun phrase "Swan song".