In a manner showing heated argument, dispute, or tendency to quarrel; argumentatively and combatively.
From 'contentious' (prone to argument) plus -ly (adverbial suffix). 'Contentious' comes from Latin contentiosus, meaning quarrelsome.
People who speak 'contentiously' aren't just disagreeing—they're actively quarreling and making it heated; it's the adverb form that turns a simple disagreement into a dramatic conflict.
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