ビッグマウス

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Meanings

1

noun

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

ビッグ・マウス
- ビッグマウス
  Variant with interpunct; less common but seen in some contexts.
- ビッグ・マウス

大おお口ぐち
大口 can also mean 'big mouth' in a literal sense (large mouth) or 'large order', while ビッグマウス is strictly about boastful talk.
ほら吹ふき
ほら吹き emphasizes telling tall tales or lies, while ビッグマウス focuses on loud, boastful, or indiscreet speech.

Loanword from English 'big mouth', adopted into Japanese with the same figurative meaning.