What defines a cycle on a jet engine?
A cycle is a start to a shutdown.  Lets say there is a flight that is loaded with pax, bags, and fuel.  They push back and start both engines since the weather is good and their at an outstation.  As they taxi to the departure runway, BAM, ground calls up saying there is a groundstop for the hub and its going to be about 30 minutes.  The flight pulls into some empty ramps space, and shuts down both engines.  Groundstop lifts, both engines started again, and the flight departs.  After landing, pulling into the gate, and shutting down the engines, we can say that for this flight, each engine went through two cycles.  ALL of this info is logged and maintenance can access it.  With some of the newer engines and higher service packages, OEM