n. One who belongs to a forum and uses a majority of their posts to be obnoxious and/or to pester their fellow forum members.

When you eat dirt for the first time and leave your family to build a shack in the woods

1) Anyone who engages a troll intentionally or unintentionally, sometimes starting a flamewar. The people who react to a troll are trolls themselves. After all, if no one engaged the troll nothing would happen. There would be no trolls if there were no trolling idiots to engage them and feed them.

2) Anyone who feeds a troll.

An idiot who manages to lumber around and behave generally like a troll in whatever fairy tale/fictional book you like. Often this is a very negative term.