How to say "bye-bye" in Japanese

• バイバイJLPT N2approx.
  interjectionA colloquial 'bye-bye; goodbye' used in casual conversation. It is less common, so it suits relaxed spoken farewells rather than formal situations.
  診察室しんさつしつを出でる間際まぎわ、先生せんせいが「バイバイ」と手てを振ふってくださいました。↗

  Just as we were leaving the exam room the doctor waved his hand saying, 'bye-bye'.
• バイビー
  interjectionA colloquial 'bye-bye; goodbye' for casual speech, and a separate word from バイバイ. It is less common, so it is a marginal choice for this sense.
• ノシ
  unclassifiedInternet slang covering 'bye-bye; see you later', used in online writing rather than spoken conversation. It is a poor choice for farewells in speech; keep it to casual online messages.
• したっけ
  interjectionCovers 'goodbye; see you later', with 'bye-bye' as a further sense. It is less common, and it suits partings where you expect to meet again more than neutral 'bye-bye' farewells.

All four are less common farewells: 「バイバイ」 and 「バイビー」 are colloquial 'bye-bye' words for casual talk, 「ノシ」 is internet slang used in online writing, and 「したっけ」 is mainly a 'goodbye; see you later' expression.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• バイバイbye-bye
• バイビーbye-bye
• ノシbye-bye
• したっけgoodbye