Indicates useless talk; often has a negative undertone, suggesting the speaker's words are wasteful. The meeting was unproductive, filled with his endless prate.
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Verb Form
'Prate' is a verb; you can't 'be' prate or 'have' prate, you can only 'prate about' something. Instead of helping, he just prated on about unrelated issues.
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Casual Context
Commonly used in informal situations, not usually found in formal writing or speech. At dinner, our host started to prate about his travels.