In a stubbornly defiant way; with rebellious or insolent refusal to obey.
From 'contumacious' (adjective, from Latin 'contumacious') + '-ly' (adverb suffix). It describes the manner of acting with stubborn defiance.
When someone acts contumaciously, they're not just being stubborn—they're making a statement through their defiance, which is why the word appears so often in legal and historical documents describing famous rebels.
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