Japanese 297 - Levels of certainty

QuestionAnswer
probably, perhapsぶんtabun
(He)'s probably already sleeping.ぶん もう て いる。tabun mou nete iru.
The book is probably in the library.ほん は ぶん しょかん に あります。hon ha tabun tosyokan ni arimasu.
probably, perhapsおそらくosoraku

Same degree of confidence as ぶん, but more formal.

That is likely not the correct answer.おそらく それ は ただしい こたえ で は ありません。osoraku sore ha tadasii kotae de ha arimasen.
The shop is likely closed.みせ は おそらく まって います。omise ha osoraku simatte imasu.
surely, certainlyきっとkitto
(Your) older sister will certainly come.きっと おねえさん は ます。kitto oneesan ha kimasu.
It will surely snow.きっと ゆき が ります。kitto yuki ga hurimasu.
They will surely be late.きっと かれら は おくれる。kitto karera ha okureru.
sure, certain; reliableたしtasika
surely; certainly; indeedたしか にtasika ni

Where きっと expresses a strong belief or confidence that something will happen or is the case, たしか に often additionally implies that the speaker has evidence or reasoning to support the certainty, or has personally verified the fact.

That shop is certainly closed.たしか に あの みせ は まって いる。tasika ni ano mise ha simatte iru.
This is indeed his wallet.たしか に これ は かれ の さい です。tasika ni kore ha kare no saihu desu.
That's certainly the case, isn't it?たしか に そう です ね。tasika ni sou desu ne.
definitely; necessarily; invariablyかならkanarazu

かならexpresses a strong commitment or assurance that something will happen or is the case. It's often used to make promises or to express unwavering certainty.

(You) will definitely find the answer.かならず こたえ を つけます。kanarazu kotae wo mitukemasu.
(He) always remembers the birthday without fail.かならず たんじょう を おぼえて います。kanarazu tanzyoubi wo oboete imasu.

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