notorious

Notorious comes from Late Middle English notoryous, from Medieval Latin nōtōrius, meaning evident or well-known, but also infamous. That in turn traces to Latin nōtus, 'known' or 'recognized,' the perfect passive participle of nōscō, 'to become acquainted with,' from the Proto-Indo-European root *ǵneh₃-, 'to know.'

Even in Medieval Latin, nōtōrius already carried both senses at once — well-known and infamous — so the word's slide toward its darker meaning in English wasn't a later invention but an inheritance already built into its source.

It shares its root with Latin nōtus and its many Romance descendants, including Italian notorio, Spanish notorio, Catalan notori, and Portuguese notório, all of which still mean simply 'well-known' rather than carrying the negative shadow English gives it.