Noun. A metatroll is a troll
who develops such an obsessive, pathological dislike of another member of a newsgroup or discussion forum that he even attacks that member on other newsgroups or discussion forums to which they do not even belong and may have no knowledge of (hence 'meta': outside of, or beyond (the original newgroup or forum)). In extreme cases, the metatroll may even create an entry in an online dictionary for the online name of his nemesis, thereby broadcasting his hatred of them to the entire online world.
Metatrolls often develop deep hatred of other people online because of feelings of inferiority, having been consistently humiliated by their superior knowledge, intelligence or command of language, or their serene unflappability in the face of the metatroll's attempts to annoy and irritate them by his persistent trolling). See metasapien