ビッグマウス

noun

big mouth; loudmouth; braggart

Refers to a person who talks boastfully, indiscreetly, or too much. Often used critically.

• 彼かれはビッグマウスだけど、実じつ力りょくはない。

  He's a big mouth, but he has no real ability.

• あのビッグマウスにはうんざりだ。

  I'm fed up with that loudmouth.