A concept from science fiction (usually cyberpunk). The idea is that in the future, corporations will continue to merge or buy each other up until only a few (usually fewer than 10) monolithic coroporations are left, and these corporations will be capable of producing just about anything a consumer might need. The result would be stupendously fierce infighting amongst the remaining megacorporations (megacorps for short). Some sci-fi pieces go on to suggest that megacorps will eventually replace governments as seats of power.