What are the differences when using the following words/phrases to mean "perhaps", "maybe" or "probably"?

  • 多分
  • 恐らく
  • 蓋し {けだし}
  • もしかして
  • ひょっとして
  • なかろう (negative -> probably not)
  • だろう / でしょう / であろう
  • かも知れない

Please add any other words/phrases that provide similar meanings.

N.B I hope istrasci doesn't mind me using his favorite question title pattern here :P

  • 1
    You have であろう and なかろう but not だろう? For shame. :p (Regarding なかろう, the most obvious thing that comes to mind is that it's a literary construction. Colloquial Japanese would probably use ないだろう or its variants.)
    – Zhen Lin
    Sep 9, 2011 at 9:44
  • @Zhen I thought でしょう should have already covered だろう because they are only different in informal vs formal, but, fine! I've added it to the list ... do you also want でござろう added along? :P
    – Lukman
    Sep 9, 2011 at 9:47
  • であろう is a variant of だろう, just as である is a variant of だ. (The relationship is exactly parallel.)
    – Zhen Lin
    Sep 9, 2011 at 9:49
  • @Zhen I see. Then I put であろう in the same line as だろう and でしょう.
    – Lukman
    Sep 9, 2011 at 9:57
  • Big time! Actually, I started intentionally use the same title format because it will help interested users find similar posts. So when they pull up or search for any one of these, they should see the others that might interest them as well.
    – istrasci
    Sep 9, 2011 at 16:54

1 Answer 1


Well, the first problem is that they often mix together, and are thus rather hard to tell apart…

Should I give exclusive nuances, I'd go like this:

  • 多分: Maybe. I don't know. 多分行きます。 (very often, 多分行くかもしれません)
  • 恐らく: has a negative nuance by the kanji. 恐らく雨が降る
  • 蓋し {けだし}: (never heard, I won't conjecture)
  • もしかして: By any chance, would it be possible that… もしかして、彼女だったの?
  • ひょっとして: Small, unimportant thing that may help you: ひょっとしたら、誰も気づかない

  • かも知れない: way to round the corners, not to affirm too much. 彼が好きかもしれない。

なかろう / だろう / でしょう / であろう deserve their own question if it hasn't been done yet, for it can mean many things. Basically, it can be a conjecture in which you want people to know that you think like this (the cake you give to your friend: おいしいでしょう? The description of a party on facebook that happens it the middle of a thursday afternoon: 誰も来ないだろう!)

  • I have never heard of 蓋し either, but my dictionary says that it means "probably" so I'm hoping to see how it's actually being used ..
    – Lukman
    Sep 9, 2011 at 10:30
  • Regarding であろう, let's limit it to the usage that is similar to "僕が好きであろう曲を教えてください" (i.e. not as a sentence ending thing) ..
    – Lukman
    Sep 9, 2011 at 10:34
  • @Lukman: It is not possible to use だろう as a modifier, as far as I know. Grammatically speaking it is not so different from using, say, 行こう as a modifier.
    – Zhen Lin
    Sep 9, 2011 at 15:37
  • @Zhen Are you referring to the usage of であろう in 僕が好きであろう曲? I found plenty of results in Google searches for "好きであろう[noun]" so I don't think that this usage is really ungrammatical or even colloquial ..
    – Lukman
    Sep 9, 2011 at 15:43
  • 1
    @istraci: when I hear girls say "彼が好きかもしれない", they in fact state that they definitely like the guy. かもしれない is in quite many cases almost as meaningless as "you know" in American English. It's just a way to ensure you didn't formally said what you thought by faking not being sure.
    – Axioplase
    Sep 12, 2011 at 1:33

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