Monopoly: market situation where one producer controls supply of a good or service, and where the entry of new producers is prevented or highly restricted.

http://www.businessdictionary.com/definition/monopoly.html

Patent troll: uses patents as legal weapons, instead of actually creating any new products or coming up with new ideas. Instead, trolls are in the business of litigation https://www.eff.org/issues/resources-patent-troll-victims

Why does Chinas scale and size effect tariffs?