How to say "authenticity" in Japanese

• 真偽しんぎCommon
  nounCovers whether something is true or false, genuine or not. It is the general word for verifying authenticity of claims, information, or objects, asking simply which of the two it is.
• 真贋しんがんCommon
  nounSpecifically the distinction between the genuine article and a spurious one, typically when experts examine paintings, antiques, or documents to determine whether a work is authentic or a forgery.
  鑑定かんていをする時ときには、絵えの真贋しんがんや保存ほぞん状態じょうたい等とうを調しらべる為ため、持ち主もちぬしに本物ほんものを借かりたりしなければいけなくなる。↗

  When it is appraised, in order to check the authenticity and state of preservation of the painting, the real thing has to be borrowed from its owner.
• 信頼性しんらいせいCommon
  nounReally means reliability or credibility rather than genuineness. Use it when 'authenticity' concerns whether data, a source, or testimony can be trusted; it is not the word for spotting a forgery.
  これらのすべての装置そうちは信頼性しんらいせいに欠かけている。↗

  All these devices are unreliable.

For whether something is genuine or a fake choose 真偽 or 真贋; for trustworthiness or credibility choose 信頼性; 真偽 is more general, 真贋 often evokes judging artworks and documents.

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

• 真偽しんぎtruth or falsehood
• 真贋しんがんgenuineness or spuriousness
• 信頼性しんらいせいcredibility
• 信憑性しんぴょうせいauthenticity
• オーセンティシティauthenticity
• 信疑しんぎbelief or doubt
• 真実性しんじつせいfidelity
• 現実味げんじつみ(sense of) reality