How to say "accomplice" in Japanese

• 相棒あいぼうCommon
  nounCovers 'partner, pal', and by extension an accomplice, often one's partner in crime. The nuance is a companion or sidekick, frequently with a friendly or loyal tone; it is the natural choice when the sense is 'partner' rather than criminal guilt.
  こいつ、さっきまで俺おれの相棒あいぼうだったのに、もう寝返ねがえりやがった。↗

  This rat, up until just now he was my partner and now he's gone and turned on me.
• 同類どうるいCommon
  no-adjectiveBasically means 'the same kind, fellow of the same sort'; 'accomplice' is only a marginal gloss, typically in the negative phrase implying one is no better than the other. For a criminal accomplice, this is seldom the word you want.
  石炭せきたんは化学的かがくてきにダイヤと同類どうるいである。↗

  Coal is chemically allied to diamonds.

Use 相棒 for a partner or trusted sidekick, sometimes affectionately or for a partner in crime; use 同類 for 'the same kind', and only marginally for an accomplice.

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

• 相棒あいぼうpartner
• 同類どうるいthe same kind
• ぐるaccomplice
• 加担者かたんしゃaccomplice
• 共犯者きょうはんしゃaccomplice
• 従犯じゅうはんaccomplice
• アコンプリスaccomplice
• 共謀者きょうぼうしゃconspirator
• 片割れかたわれone of the same group
• 片棒担ぎかたぼうかつぎpartner (in crime)