What is a "tropical cyclone"

http://www.wunderground.com/blog/JeffMasters/show.html

The tropics have fallen silent the past two days, with no named storms anywhere on the planet. It's not unusual to see a quiet period for tropical cyclones in July, which lies before the climatological peak months of August, September, and October in the Northern Hemisphere (a tropical cyclone is the generic term for all tropical depressions, tropical storms, and hurricanes/typhoons). The tropical cyclone-free period will likely be short lived, though, as Invest 90E, located in the Eastern Pacific about 1,050 miles southwest of the southern tip of Mexico's Baja Peninsula on Monday morning, may develop into a tropical depression by Wednesday. This system is something residents of Hawaii should keep an eye on.