N2 — outside your level filter

に決きまっている

にきまっているni kimatte iruN2casual

savor + of course it is

ajiwau ni kimatte iru

of course it is; is bound to be — treated as beyond argument

meaning: of course it is

Same meaning

味あじわう
〜に決きまっている
味あじわうに決きまっている

そんな話はなし、嘘うそに決きまってるじゃない。

sonna hanashi, uso ni kimatteru ja nai.

A story like that has got to be a lie. casual

今いまから走はしっても、終電しゅうでんには間まに合あわないに決きまっている。

ima kara hashitte mo, shuuden ni wa ma ni awanai ni kimatte iru.

Even if we run now, there's no way we'll make the last train. neutral

Same meaning15

probably; might; should be

だろうprobably; I suppose (plain style)attaches at
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

of course it is; is bound to be — too obvious to argue

そんな話はなし、嘘うそに決きまってるじゃない。
sonna hanashi, uso ni kimatteru ja nai.
A story like that has got to be a lie. casual
あいつの話はなし、嘘うそに決きまっている。
aitsu no hanashi, uso ni kimatte iru.
What that guy says is bound to be lies. casual
今いまから走はしっても、終電しゅうでんには間まに合あわないに決きまっている。
ima kara hashitte mo, shuuden ni wa ma ni awanai ni kimatte iru.
Even if we run now, there's no way we'll make the last train. neutral
一人ひとりでこの量りょうを運はこぶのは無理むりに決きまっています。
hitori de kono ryou o hakobu no wa muri ni kimatte imasu.
Carrying this much alone is obviously impossible. neutral

How it's formed3

All forms3

に決きまってるnikimatterucontraction
味あじわうに決きまってる
the everyday spoken shape, い dropping from ている here as everywhere else (そんなの嘘うそに決きまってるよ).

pastに決きまっていたnikimatteita
味あじわうに決きまっていた
politeに決きまっていますnikimatteimasu
味あじわうに決きまっています

Notes

Polite です／ます changes nothing (決きまっています still shuts down disagreement). It
stays out of formal writing and out of anything said upward.