To make sour, harsh, or bitter; to embitter or exacerbate.
From Latin acerbus (sour, harsh) plus -ate (verb-forming suffix). English adopted this in the 16th century but it remained quite rare.
While we commonly use 'exacerbate,' the older 'acerbate' is its forgotten cousin—both mean to make worse, but acerbate specifically hints at bitterness and harshness.
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