言わずもがな

Meanings

1. Expression

   (it) goes without saying; needn't be said

2. Expression, No-adjective

   that should rather be left unsaid

• 言いわずもがなだ。

  You know what it is.

• そんなことは言いわずもがなだ。

  That goes without saying.

• 言いわずもがなのことを言いってしまった。

  I should not have said that.