To make brutal or cruel; to treat someone with excessive harshness or violence.
From 'brutal' (itself from Latin 'brutus') plus the verb-forming suffix '-ise' (British spelling) or '-ize' (American). Emerged in the 18th century to describe the process of becoming or making brutal.
The difference between British 'brutalise' and American 'brutalize' is just a spelling convention—but it matters for consistency and professional writing in different English-speaking countries!
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