Synonyms of 'mouth off'
▷ See mouth
rantDictionary, rave, spout (informal)
He received a yellow card for mouthing off to the referee.
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If you declaim, you speak dramatically, as if you were acting in a theatre.
He used to declaim verse to us with immense energy.
I don't rant and rave or throw tea cups.
Thesaurus for mouth off from the Collins English Thesaurus
to give an opinion or speak emotionally, often without much care or consideration