How to say "majority" in Japanese

• 大半たいはんJLPT N3approx.Common
  no-adjectiveThe everyday word for the 'most (of)' sense: more than half of a group, quantity, or stretch of time. Use it for neutral statements such as 'most people agreed' or 'most of the day'.
  ここの学生がくせいは大半たいはんが真面目まじめである。↗

  The students are for the most part diligent.
• 成年せいねんJLPT N1approx.Common
  nounThis is the legal sense only: 'majority' as in reaching adult age. It is never used for 'most of'; if you mean the greater part of something, this is not the word you want.
  あなたの娘むすめさんはいつ成年せいねんに達たっしたのですか。↗

  When did your daughter come of age?
• 大方おおかたJLPT N1approx.Common
  no-adjectiveRefers to the large or greater part of something, much like 大半. In meaning it overlaps with that word, so either can express the idea of 'most of a group'.
  実じつのところ、いかなるスピードで移動いどうするにせよ、北極ほっきょく熊くまは他たのおおかたの哺乳ほにゅう動物どうぶつの２倍ばいのエネルギーを消費しょうひする。↗

  In fact, to move at any speed the polar bear uses twice as much energy as do most other mammals.
• 過半数かはんすうJLPT N2approx.Common
  nounThe word for a numerical majority: more than half of a countable total. Typical contexts are votes, seats, or survey results, where you say that a side won or holds a majority.
  合格者ごうかくしゃの過半数かはんすうは大学だいがく出身者しゅっしんしゃであった。↗

  The majority of the successful candidates were university graduates.
• 大部分だいぶぶんJLPT N3approx.Common
  nounEveryday word for the 'most part' or 'greater part' of something — people, things, or a portion of time or text. In most contexts it is interchangeable with 大半 for the 'most of' sense.
  石炭せきたんは大部分だいぶぶんが炭素たんそから成なっている。↗

  Coal consists mostly of carbon.

For the 'most of' sense choose 大半 or 大部分 (also 大方), for a numerical majority choose 過半数, and reserve 成年 for the legal 'age of majority'.

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

• 大半たいはんmajority
• 成年せいねんadult age
• 大方おおかたlarge part
• 過半数かはんすうmajority
• 大部分だいぶぶんmost part
• マジョリティーmajority
• 賛成多数さんせいたすうmajority (vote)
• 多くおおくmajority (of)
• 多数たすうmajority