Stubborn, bad-tempered, and difficult to deal with; quarrelsome and irritable.
Of obscure origin, possibly from obsolete English 'cantanker' or related to Latin 'contenciosus' (contentious), though the exact etymology is debated, appearing in English by the 1600s with the '-ous' suffix meaning 'full of.'
Nobody knows exactly where 'cantankerous' came from—it's one of English's orphan words with a mystery biography, but its very sound feels grumpy and stubborn, so it stuck around despite scholars never solving its origin story.
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