板上釘釘

Simplified: 板上钉钉

bǎnshàngdìngdīng ㄅㄢˇ ㄕㄤˋ ㄉㄧㄥˋ ㄉㄧㄥ

    • that clinches it
    • that's final
    • no two ways about it

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
a nail driven into a board
Meaning
Settled and unchangeable; a done deal.

Sources