How to say "informant" in Japanese

• インフォーマント
  nounThe katakana loanword, used chiefly in research and survey settings for a person who supplies information, such as a survey respondent. Neutral and technical, with no hint of betrayal.
  インフォーマントはアメリカ人あめりかじん２０人にん、イギリス人いぎりすじん２１人にんという構成こうせいである。↗

  The informants we used consisted of twenty Americans and twenty-one British.
• 情報提供者じょうほうていきょうしゃ
  nounThe neutral, descriptive term: literally a person who provides information. It fits any context where someone supplies information, including to the police or news media, and carries no judgment by itself.
• 内通者ないつうしゃ
  nounSomeone inside a group or organization who secretly passes information to an outside party — a mole. The word stresses the breach of trust, so it implies betrayal of one's own side.
• 密告者みっこくしゃ
  nounSomeone who secretly informs on others, typically to the authorities — an 'informer' or 'snitch'. The word is strongly disapproving, painting the person as a betrayer.
• いぬJLPT N5approx.Common
  nounA derogatory word, usually written in kana, for someone who sells out their companions — a 'rat' or 'squealer'. It is an insult hurled at a snitch rather than a neutral description.
  気きをつけて。警察けいさつの犬いぬがかぎ回まわってる。↗

  Watch out! A police spy is snooping around.

Choose 「インフォーマント」 for research or survey contexts, 情報提供者 as the neutral word for an information source, and 内通者, 密告者, or 「いぬ」 when the informing is secret or treacherous, the last being openly insulting.

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

• インフォーマントinformant (often with regard to survey respondents)
• 情報提供者じょうほうていきょうしゃinformant
• 内通者ないつうしゃmole
• 密告者みっこくしゃinformer
• いぬsquealer