How to say "serious" in Japanese

• まじCommon
  na-adjective, nounA colloquial shortened form covering the 'not joking' sense of serious — the 'seriously?' or 'no joke' reaction to surprising news. It is casual speech, not the word for describing a serious person or problem.
  「・・・おい・・・おい、先生せんせい！」「え？・・・あ、ああ」「マジだいじょうぶ？休講きゅうこうにしたら？」↗

  "...Hey...Hey, teacher!" "Eh? Oh." "Are you really OK? Shouldn't you cancel the lesson?"
• 大事だいじJLPT N4approx.Common
  na-adjectiveCovers serious in the sense of consequential — a serious matter, mistake, or injury whose outcome matters. The emphasis falls on importance: something you must not treat lightly.
• 大切たいせつJLPT N5approx.Common
  na-adjectiveChiefly means important or precious — treasuring people and things — and its 'serious' sense is the same consequential one as 大事. For grave or earnest 'serious', it is seldom the word you want.
  柔道じゅうどうでは力ちからより技わざのほうが大切たいせつである。↗

  In judo, technique is more important than strength.
• 真面目まじめJLPT N4approx.Common
  na-adjective, nounCovers the earnest, sober sense of serious: a serious person, expression, or attitude. It describes character — someone earnest and grave who does not joke around.
  サムは仕事しごとに関かんしてまじめです。↗

  Sam is serious about his work.
• 真剣しんけんJLPT N3approx.Common
  na-adjectiveSerious in the sense of wholehearted and grave intent: being serious about something, or a serious discussion. Where 真面目 describes character, 真剣 conveys the intensity of the moment.
  ジョージは勉強べんきょうに真剣しんけんでない。↗

  George is not serious about his study.

Use 真面目 for an earnest, sober character, 真剣 for wholehearted gravity of intent, 大事 for matters of consequence, 大切 chiefly for 'important/precious', and 「まじ」 only in casual speech for 'no joking'.

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

• まじserious
• 大事だいじimportant
• 大切たいせつimportant
• 真面目まじめserious
• 真剣しんけんserious
• 深刻しんこくserious
• 重大じゅうだいserious
• シリアスserious
• 真摯しんしsincere
• 重度じゅうどsevere (illness, disability, etc.)
• 重篤じゅうとくcritical (condition)
• 甚大じんだいvery great
• 大おおlarge
• 大だいlarge
• 難しいむずかしいdifficult
• 重々しいおもおもしいserious
• 厳粛げんしゅくgrave
• 由々しいゆゆしいgrave
• 多大ただいgreat (quantity, amount, etc.)
• 甚だしいはなはだしいextreme
• 険悪けんあくdangerous
• がちserious
• ただならないunusual
• 由々しきゆゆしきgrave
• けちょんけちょんthorough (criticism, defeat, etc.)
• ただならぬunusual
• 難しげむずかしげdifficult
• お堅いおかたいstrict
• 深重じんじゅうprofound
• 大変たいへんserious
• リアルserious
• 厚いあついserious (of an illness)
• えらいawful
• 重たいおもたいheavy (feeling, atmosphere, etc.)
• 切実せつじつpressing
• もっともらしいsolemn
• まともhonest
• とんだterrible
• 本格的ほんかくてきfull-scale
• 重じゅうserious
• 肩が凝るかたがこるserious
• 本式ほんしきin earnest
• 重ったいおもったいheavy (feeling, atmosphere, etc.)
• 重いおもいimportant (position, responsibility, etc.)
• ごりごりhardcore