bye-bye

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

Informal. goodbye.

noun

Baby Talk. sleep.

Idioms

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

Origin of bye-bye

1700–10; apparently orig. nursery phrase used to lull a child to sleep, later construed as reduplicative form of bye, short for goodbye
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019