1 B2 idiomatic informal
To speak rudely or disrespectfully to someone, especially a person in authority.
"He got sent out of class for mouthing off at the teacher in front of everyone."
inseparable
mouth off
B2 informal inseparable intransitive
To speak rudely, loudly, or disrespectfully; to say offensive or boastful things without appropriate restraint.
In plain English
Say rude or loud things to someone, or talk in a way that shows no respect.
What does "mouth off" mean?
2 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B2 idiomatic informal
To talk loudly, boastfully, or without appropriate restraint about one's opinions or achievements.
"He's always mouthing off about how much money he earns — it's embarrassing."
inseparable
Usage tip
Used in both British and American English. Usually critical — the speaker disapproves of the behaviour. Can mean talking rudely to an authority figure, boasting, or expressing opinions loudly and inappropriately. Often followed by 'at' or 'about'.
Words that pair with "mouth off"
Natural word combinations native speakers use most often.
teacher boss audience about stop always
How to conjugate "mouth off"
The five tense forms you'll use most often.
Base
mouth off
I/you/we/they
3rd person
mouths off
he/she/it
Past simple
mouthed off
yesterday
Past participle
mouthed off
have + pp
-ing form
mouthing off
continuous
Hear "mouth off" in the wild
Listen to native speakers using "mouth off" in real YouTube videos — click a clip to watch it on Looplines.
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