だろう (darou)

Related patterns8

Similar

はずだ
はずだ stakes the claim on reasoning or evidence, だろう is an unbacked guess. Swapping them changes how accountable the speaker is for being wrong.
でしょう
でしょう is the polite guess, だろう the plain one, spoken だろう sounds male and blunt. Writing treats it as ordinary.
今いまに
だろう softens any sentence, 今いまに instead commits the speaker. The two can be used together (今いまに困こまることになるだろう), but 今いまに never softens like だろう.
かな
だろう states a guess plainly, and is the usual written form (来くるだろう). かな turns that guess into a question murmured half to oneself.
まい
だろう negates the verb itself, and that's what people actually say (降ふらないだろう). まい bundles "won't" into one old word, seen in writing, never in speech (降ふるまい).
のではないか
だろう states a guess and stands behind it (古ふるすぎるだろう). のではないか turns it into a question, leaving room to disagree (古ふるすぎるのではないか).
と考かんがえられる
だろう is your own guess, and works in any spoken setting (明日あしたは雨あめだろう). と考かんがえられる is written and formal only, backed by stated evidence.

Lookalikes

ことだろう
plain だろう alone just guesses, probably true (明日あしたは晴はれるだろう). ことだろう instead exclaims a strong feeling, not a guess at all.

Same meaning15

probably; might; should be

でしょうprobably; I suppose; right?attaches at
はずだshould; ought to; is supposed toattaches at
かもしれないmight; may possiblyattaches at
かなI wonder; maybe (wondering aloud)attaches at
かねないcould well (and it wouldn't be good); there's a real chance thatattaches at
まいsurely won't; I shall never — the classical negative of だろう and of （よ）うattaches at
ないとも限かぎらないyou can't rule out that it will happen; it may happen anywayattaches at
に違ちがいないmust be; surely is (a confident conclusion)attaches at
に決きまっているof course it is; is bound to be — treated as beyond argumentattaches at
に相違そういないbeyond doubt; there is no doubt that (written, formal)attaches at
恐おそれがあるthere is a danger that; is at risk of (something unwelcome)attaches at
そうもないshows no sign of; doesn't look like it willattaches at
と考かんがえられるit can reasonably be concluded that; is to be regarded asattaches at
と思おもうI think that; in my opinionattaches at
ような気きがするI have a feeling that; it seems to me thatattaches at

All examples4

probably — plain-style guessing, the usual choice in written analysis

誘さそえば、彼かれも来くるだろう。
sasoeba, kare mo kuru darou.
If we invite him, he will probably come too. neutral
この問題もんだいは専門家せんもんかでも解とけないだろう。
kono mondai wa senmonka demo tokenai darou.
Even an expert probably couldn't solve this problem. neutral
来年らいねんには状況じょうきょうも変かわっているだろう。
rainen ni wa joukyou mo kawatte iru darou.
By next year the situation will likely have changed too. neutral

right?; come on — clipped だろ？ pushing the listener to agree, rough and casual

な、言いった通とおりだろ？
na, itta toori daro?
See? Just like I told you, right? casual

How it's formed3

All forms2

だろdarocontraction
味あじわうだろ
clipped and blunt — お前まえも行いくだろ？ sounds rough and masculine
のだろうnodaroualternant
味あじわうのだろう
the explanatory の in front turns the guess into wondering aloud about a reason — 穴あなの中なかはどうなっているのだろう; んだろう is the spoken spelling.

Notes

だろう swallows だ like でしょう does (雨あめだろう, never ×雨あめだだろう).
Spoken だろう sounds masculine and blunt; だろ？ presses, checking the
listener agrees, tone matey to aggressive.