Treated someone badly, roughly, or unfairly; handled with cruelty or disrespect.
From 'mis-' (badly) plus 'treat,' from Old French 'traitier' (to handle/manage). The prefix 'mis-' reverses the positive meaning.
The prefix 'mis-' is one of English's most versatile word-builders—it instantly creates opposites (treat becomes mistreat, fortune becomes misfortune, understanding becomes misunderstanding), which is why people can so creatively coin new words by adding it to verbs.
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