/ pəˈvɜːs; NAmE pərˈvɜːrs/ adjective
showing deliberate determination to behave in a way that most people think is wrong, unacceptable or unreasonable :
a perverse decision (= one that most people do not expect and think is wrong)
She finds a perverse pleasure in upsetting her parents.
Do you really mean that or are you just being deliberately perverse ?
► per·verse·ly adverb :
She seemed perversely proud of her criminal record.
► per·vers·ity noun [ U ]:
He refused to attend out of sheer perversity.
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WORD ORIGIN
late Middle English (in the sense turned away from what is right or good ): from Old French pervers(e) , from Latin perversus turned about, from the verb pervertere , from per- thoroughly, to ill effect + vertere to turn.