In a manner that relates to crime or illegal activity; also used informally to mean 'to a shocking or excessive degree.'
From criminal (one who commits crimes) + -ly (adverb suffix), with criminal coming from Latin criminalis (relating to accusations or crimes). The informal usage grew in the 20th century.
When someone says something is 'criminally underrated,' they're using legal language to express moral outrage — it's a clever exaggeration that treats artistic injustice like actual crime, showing how language borrows from dramatic domains to express intensity.
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