How to say "certainly" in Japanese

• 是非ぜひJLPT N4approx.Common
  adverbCovers 'certainly' in the sense of 'by all means, without fail': urging someone to do something or voicing a keen wish of your own, as in 'do come' or 'I'd certainly like to go'.
  「キャッチボールしようか」「よし、是非ぜひやろう」↗

  "How about playing catch?" "Sure, why not?"
• もちろんJLPT N4approx.Common
  adverbThe go-to word for 'of course', normally written in kana alone: use it to answer a question or state that something goes without saying — 'Certainly I'll come.'
  「ご一緒いっしょしてもいいですか」「もちろんです」↗

  "May I go with you?" "Of course."
• ともCommon
  particleEmphatic agreement, usually as a short reply: asked 'Will you come?', you answer with a firm 'Certainly!'. It asserts the point rather than merely conceding it.
  パターソン博士はかせ：いいですとも。ココの猫好ねこずきを知しっていますか。↗

  Dr. Patterson: Sure. Do you know about Koko's love for cats?
• 無論むろんJLPT N1approx.Common
  adverbCovers the same ground as もちろん — 'of course; certainly; naturally' — presenting something as self-evident; the two are near-interchangeable, so for plain 'of course' もちろん remains the default choice.
  むろん信用しんようしていいとも。君きみにヨタ情報じょうほうを教おしえたことが一度いちどでもあったかい。↗

  Of course you can trust me. Have I ever given you a bum steer before?
• てっきりJLPT N1approx.Common
  adverbNot plain 'certainly' but 'surely': it voices a firm assumption about how something would turn out — 'I was certain he'd come' — often recalling an expectation that proved wrong.
  てっきりあなたが我々われわれといっしょに来こられるものと思おもっていました。↗

  I took it for granted that you would come with us.

Choose ぜひ for eager urging or a keen wish, 「もちろん」 (or 無論) for 'of course' statements of the obvious, 「とも」 for emphatic agreement, and 「てっきり」 for something you were sure would happen.

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

• 是非ぜひcertainly
• もちろんof course
• ともcertainly
• 無論むろんof course
• てっきりsurely
• さぞsurely
• 必ずかならずalways
• ぜひぜひcertainly
• まさにexactly
• 喜んでよろこんでwith pleasure
• まさしくcertainly
• しかとcertainly
• さぞかしcertainly
• けだしcertainly
• 必ずやかならずやcertainly
• 相違なくそういなくcertainly
• 努努ゆめゆめcertainly
• １２０％ひゃくにじゅっパーセントcertainly
• よもやsurely (not)
• 必定ひつじょうinevitably
• 定めてさだめてsurely
• 確かにたしかにsurely
• もしかしなくてもno need to guess
• さぞやsurely
• もちのろんof course
• 間違いなくまちがいなくclearly
• そのまさかだyes it is!
• まさにreally (ought to)
• ＯＫ牧場オッケーぼくじょうOK
• おうともof course
• 一定いちじょうveritably
• 紛う方なくまごうかたなくundoubtedly
• 大丈夫だいじょうぶcertainly
• どうぞby all means
• まさかcertainly (not)
• とにかくreally
• いかにもabsolutely
• 御意ぎょいcertainly
• いかさまsurely
• 何様なにさまabsolutely