How to say "principal" in Japanese

• メインCommon
  no-adjectiveCovers the adjective sense 'main; principal', usually meaning the chief or most prominent thing, often in casual contexts. It is a loanword, so it sounds less formal than 主要 or 主.
  昨日きのうの競馬けいばのメインレースは、とってもかたくおさまったよ。ああいうのを、銀行ぎんこうレースって言いうんだよね。↗

  The main race yesterday was no surprise. That's the kind of race you can bank on.
• 主おもCommon
  na-adjective, nounAn adjective meaning 'chief; main; principal; important'. It typically appears before another noun to mark the most important one among several, and reads おも in that use.
  読書どくしょが彼かれのおもな楽たのしみだ。↗

  Reading is his chief amusement.
• 校長こうちょうJLPT N4approx.Common
  nounThe noun for the person: the principal or headmaster of a school. When English 'principal' refers to the head of a school, this is the word you want.
  私わたしたちの校長こうちょう先生せんせいは授業じゅぎょうはしません。↗

  Our principal does no teaching.
• 元本がんぽんCommon
  nounThe financial sense of 'principal': the original sum of money invested or lent, as opposed to interest or gains. Use it only in money and investment contexts.
• 主要しゅようJLPT N3approx.Common
  na-adjective, nounA formal adjective meaning 'chief; main; principal; major', as in the most important roads, cities, or reasons. It suits written or formal descriptions better than メイン.
  日本にっぽんの主要しゅよう作物さくもつは米こめである。↗

  The main crop of Japan is rice.

For the person, use 校長; for money, 元本; for the adjective 'main/principal', choose between 主要, 主, and 「メイン」 depending on how formal or adverbial you need to be.

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

• メインmain
• 主おもchief
• 校長こうちょうprincipal
• 元本がんぽんprincipal
• 主要しゅようchief
• 学長がくちょう(university) president
• 重要じゅうようimportant
• 元金がんきんprincipal
• 目抜きめぬきprincipal
• 原資げんしcapital
• 主たるしゅたるmain
• 主なるおもなるmain
• 主なおもなchief
• プリンシパルprincipal
• 元高もとだかprincipal (e.g. in a loan)
• 枢要すうよう(most) important
• 学園長がくえんちょうheadmaster
• 基本財産きほんざいさんfundamental property
• 主だったおもだったchief
• 本ほんmain
• 一義的いちぎてきprincipal
• 元もとcapital