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bye–bye

1 ENTRIES FOUND:
bye–bye /ˈbaɪˌbaɪ/ interjection
bye–bye
/ˈbaɪˌbaɪ/
interjection
Britannica Dictionary definition of BYE–BYE
informal
: 1goodbye often used by children or when speaking to children

go bye-bye

informal
or British go bye-byes : to go to bed used when speaking to children
US : to go away used in imitation of children's speech