How to say "reliability" in Japanese

• 信頼性しんらいせいCommon
  nounThe common, all-purpose word: the reliability of machines, systems or data, and the credibility or authenticity of information and sources. When unsure which word to use for reliability, this is the safe choice.
  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.
• 頼りがいたよりがい
  nounReliability as a personal quality: the trustworthy, reassuring sense that someone is dependable and can be leaned on. Typically used of people — a dependable colleague, a partner you can always count on.
  彼かれは頼り甲斐たよりがいのある上司じょうしだ。↗

  He is a dependable boss.
• リライアビリティー
  nounA katakana rendering of the English word itself. Because 信頼性 is the common term, this is seldom the word you want; it appears mainly in technical or academic writing that keeps the English term.
• 頼み甲斐たのみがい
  nounCovers much the same ground as 頼りがい — the sense that someone is worth relying on. It is less common, and for reliability in general it is not the word you want.
• 定時性ていじせい
  nounNot reliability in any general sense: this word means punctuality, used of public transport. Choose it only when reliability refers to trains or buses keeping to their timetable.

Use 信頼性 for reliability in general — dependable systems, credible information; 「頼りがい」 or 「頼み甲斐」 for a person's dependability; 「リライアビリティー」 only as the technical English loanword; 定時性 solely for transport running on time.

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

• 信頼性しんらいせいcredibility
• 頼りがいたよりがいreliability
• リライアビリティーreliability
• 頼み甲斐たのみがいreliability
• 定時性ていじせいpunctuality (in reference to public transport)
• 甲斐性かいしょうresourcefulness