A dubstep song that has either increased tempo, pitch or both.
It originated from nightcore, however the original nightcore community does not support the growth of any "style" other then nightcore. It cannot be made from scratch, it has to be an already made song that gets "remixed", and published.
It should be labeled as a remix, however certain youtube uploaders either tag it as nightcore or a genre. The original nightcore community does NOT support it in any way, so labeling it as nightcore is wrong.
The most popular dubstep songs that get remixed in this way are usually vocalish. The speed+tempo increase is anything from 15-30%. It can go below and over these values, but these are the usual ones. It doesn't have to be both tempo and pitch, but they usually go hand to hand since the pitch makes the vocals anime-ish, and the speed makes the wobbles and the drop hit hard and fast.
"Hey, did you hear about the new nightstep remix I made?"
"Hey bro, you were wrong. nightstep is not the same as nightcore!"