- The definition of bye-bye is a baby-talk expression used when leaving or parting.
An example of bye-bye is when a mother has a baby wave and see daddy off to work. She might say "tell Daddy bye bye."
A baby waves bye bye
- To bed; to sleep: “[Live Senate television is] a great way to go bye-bye. Pretty soon you're asleep” (William Proxmire).
Origin of bye-byeReduplication of bye2.
- (informal, often childish) Goodbye.