bye-bye

[ interjection bahy-bahy; noun adverb bahy-bahy ]

interjection

1. Informal. goodbye.

noun

1. Baby Talk. sleep.

Word History and Origins

Origin of bye-bye¹

1700–10; apparently originally nursery phrase used to lull a child to sleep, later construed as reduplicative form of bye, short for goodbye

Idioms and Phrases

Idioms

1. go bye-bye, Baby Talk.
   1. to leave; depart; go out.
   2. to go to sleep; go to bed.