What is considered a "major war"?

One of my favorite comedians, George Carlin, has a 1992 skit called "Rockets and P*nises in the Persian Gulf War," where he has a line, "This country's only 200 years old and already we've had ten major wars!" I was trying to discern his definition of "major wars." I determined eight up to 1992 (American Revolutionary War, War of 1812, Mexican-American War, American Civil War, Spanish-American War, Philippine-American War, Korean War, Gulf War). Of course the U.S. has been involved in other wars it didn't start (WWI, WWII, Vietnam War). I'm not sure whether he's also including them, but I just wanted to clarify.