Nasty: Filthy; offensive; unpleasant; morally corrupt. Documented since the late 14th century (in the “filthy” sense), but the etymology is murky. There are similar words in related languages – nestig (“foul”) in Dutch; naskot (“dirty”) in Swedish – but the OED says “the relationship between the forms is unclear.”
Nasty was all over the news last week after Republican presidential candidate Donald Trump interrupted his Democratic opponent, Hillary Clinton, during their third debate on October 19, leaning into the microphone and saying she was “such a nasty woman.”
At about :19.