How to say "extremely" in Japanese

• めっちゃCommon
  adverbThe everyday colloquial intensifier: 'super', 'really'. Use it with friends and family in relaxed conversation; it covers 'extremely' in its casual, spoken sense.
• めちゃCommon
  adverbThe same colloquial intensifier as めっちゃ, written without the doubled っ: 'very', 'so'. The two are largely interchangeable in relaxed conversation, and either works for casual 'extremely'.
• 最ももっともJLPT N4approx.Common
  adverbReally the word for 'most': it says something is highest in degree compared with others. The 'extremely' gloss is secondary, so for plain 'extremely' it is seldom the word you want.
  ケンは三さん人にんのなかでもっとも速はやく走はしります。↗

  Ken runs fastest of the three.
• ずいぶんJLPT N4approx.Common
  adverb (with と)A gentler intensifier nearer 'fairly' or 'surprisingly' than to full 'extremely': it often implies the degree is more than expected. For strong 'extremely' it usually falls short.
  私わたしたちはもうずいぶん長ながくここにいます。↗

  We've been here long enough.
• 極まりないきわまりないCommon
  suffix, i-adjectiveNot a free-standing adverb: it is added after another word to say that quality is at its utmost — rudeness that knows no bounds. Reach for it only when you want that 'in the extreme' phrasing.
  その机つくえは、乱雑らんざつ極きわまりない状態じょうたいだ。↗

  The desk is in a state of total disorder.

For casual spoken 'extremely' pick 「めっちゃ」 or 「めちゃ」; 「ずいぶん」 is milder, nearer 'fairly'; 「最も」 really means 'most'; 「極まりない」 is a set phrase meaning a quality 'knows no bounds'.

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

• めっちゃextremely
• めちゃvery
• 最ももっともmost
• ずいぶんvery
• 極まりないきわまりないextremely
• 極めてきわめてexceedingly
• 至っていたってvery much
• たいそうvery
• 至極しごくvery
• 甚だはなはだvery
• 千万せんばんexceedingly
• 何ともなんともreally
• 人一倍ひといちばい(much) more than others
• 非常にひじょうにvery
• 誠にまことにreally
• 実にじつにreally
• ひどくterribly
• 激げきextremely
• すこぶるextremely
• ばりvery
• いたくextremely
• ごくごくextremely
• すぐれてextremely
• いともextremely
• 世にもよにもextremely
• 超がつくちょうがつくextremely
• めっさextremely
• すごくextremely
• すっごくextremely
• 超のつくちょうのつくextremely
• くそほどextremely
• ものごっつextremely
• ばちくそextremely
• めっぽうextraordinarily
• こよなくexceedingly
• ことのほかexceedingly
• それはvery
• この上なくこのうえなくmost of all
• 鬼のようにおにのようにvery
• ごっつvery much
• むちゃむちゃawfully
• どちゃくそvery
• なまらvery much
• この上もなくこのうえもなくmost of all
• めちゃんこvery
• うわりvery
• めたくそvery
• 杉内すぎうちtoo
• やけにawfully
• えらくawfully
• 全然ぜんぜんextremely
• 超ちょうextremely
• めちゃめちゃvery
• むちゃくちゃawfully
• よくよくvery
• 超絶ちょうぜつsuper
• 近頃ちかごろterribly
• 猛烈もうれつvery
• 極まるきわまるextremely
• いかにもvery
• しきりにhard
• げろextremely
• ものっそいextremely
• てんでvery
• 嫌というほどいやというほどbitterly
• ぶっちゃけreally
• それはそれはvery
• しきりとhard
• くっそvery
• これまたreally
• えらいvery
• 鬼おにvery
• くそvery
• 無茶むちゃvery