Jrock is the short version for "Japanese rock", which includes Visual Kei, normal and alternative rock, but from Japanese bands. The term sometimes includes Japanese metal bands (such as Maximum the Hormone), but it's more rarely seen.
Example: The most popular Jrock band in Japan is SID, but the GazettE has a lot of fans outside the country. They play Visual Kei and DOES plays normal rock in Japanese.
A name that you call a person who thinks that he or she has skills at rapping and thinks that everything he or she spits is straight fire, but in reality it is the worst flow in the world.
Example: Man, dude tried to diss me on a track, but he a JRock, so you know that shit was hot garbage.
A nick name for someone whose first name begins with a J and doesnt listen to anyone. A head as hard as a rock. Usually a nickname given to them by their mothers