How to say "junior" in Japanese

• 後輩こうはいJLPT N2approx.Common
  nounA junior person at work, school, or similar — someone under you in seniority rather than age. This is the everyday word for a younger colleague, classmate, or club member in a mentor-like relationship.
  彼かれは私より３年ねん後輩こうはいです。↗

  He is my junior by three years.
• ジュニアCommon
  noun, prenominal modifierThe loanword, typically used as a name suffix (as in Junior) or in labels for junior categories such as sports classes. It covers the name sense of 'junior' that the other words do not.
• 年下とししたCommon
  no-adjectiveSimply 'younger' — describing a person who is younger in age, with no implication of rank or seniority. Choose this when the relationship is purely about age, not workplace or school hierarchy.
  ジョンは私より２つ年下とししただ。↗

  John is my junior by two years.
• 下級かきゅうCommon
  no-adjectiveCovers 'junior' in the sense of lower rank or grade, as in a junior officer. A formal word about hierarchical level rather than about a personal mentor-protégé relationship.
• 次席じせきCommon
  no-adjectiveReally means the person next in rank, an associate or assistant — 'junior' here only in that ranked sense. It is seldom the word you want for a junior person generally; use it for the No. 2 position.

Use 後輩 for a person junior to you at work or school, 年下 for someone simply younger, 「ジュニア」 as a name suffix or label, 下級 for lower rank or grade, and 次席 for the person next in rank.

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

• 後輩こうはいjunior (at work, school, etc.)
• ジュニアjunior
• 年下とししたyounger
• 下級かきゅうlower grade
• 次席じせきassociate
• 目下めしたsubordinate
• 従じゅうsubordinate
• 従たるじゅうたるsubordinate
• 三回生さんかいせいthird year (college) student
• 二代目にだいめsecond generation
• 小しょうyounger (of two people with the same name)