"A tropical cyclone is the generic term for a non-frontal synoptic scale low-pressure system over tropical or sub-tropical waters with organized convection (i.e. thunderstorm activity) and definite cyclonic surface wind circulation (Holland 1993)."
Depending on where this type of weather occurs it can have many different names. For example if this type of weather occurs in the "the North Atlantic Ocean, the Northeast Pacific Ocean east of the dateline, or the South Pacific Ocean east of 160E" it is a hurricane. If it occurs in the "the Northwest Pacific Ocean west of the dateline" it is called a typhoon. If this weather occurs in "the Southwest Pacific Ocean west of 160E or Southeast Indian Ocean east of 90E" it is called a severe tropical cyclone. If this weather occurs in "the North Indian Ocean" it is called a severe cyclonic storm. If this weather occurs in "the Southwest Indian Ocean" it is called a tropical cyclone.