In the United States “conspiracy theory” is the name given to explanations that differ from those that serve the ruling oligarchy, the establishment or whatever we want to call those who set and control the agendas and the explanations that support the agendas.
The explanations imposed on us by the ruling class are themselves conspiracy theories. Moreover, they are conspiracy theories designed to hide the real conspiracy that our rulers are operating.
For example, the official explanation of 9/11 is a conspiracy theory. Some Muslims, mainly Saudi Arabians, delivered the greatest humiliation to a superpower since David slew Goliath. They outsmarted all 17 US intelligence agencies and those of NATO and Israel, the National Security Council, the Transportation Safety Administration, Air Traffic Control, and Dick Cheney, hijacked four US airliners on one morning, brought down three World Trade Center skyscrapers, destroyed that part of the Pentagon where research was underway into the missing $2.3 trillion, and caused the morons in Washington to blame Afghanistan instead of Saudi Arabia.