Timing path
Beginner
One route a signal takes from one small memory in the chip to the next.
Novice
The route a signal takes from one flip-flop (or an input) through a chain of gates to the next flip-flop (or an output). It must finish within one clock period, minus a little margin.
Expert
A start point (a flip-flop clock pin or an input port), the cells and nets it passes through, and an end point (a flip-flop data pin or an output port). Timing tools compute arrival and required times for every such path and report the worst per end point.