Coupling capacitance
Beginner
The invisible electrical link between two wires running side by side, which lets a signal on one nudge the other.
Novice
Two wires next to each other, separated by insulator, form a small capacitor: a pair of conductors that store charge between them. The longer they run together and the closer they are, the larger it is, and the more a voltage change on one pushes on the other.
Expert
Grows with parallel run length and falls with spacing. At tight pitches, same-layer coupling to the adjacent wires can exceed a wire’s capacitance to ground, which makes neighbor choice a main timing and noise lever. Extraction reports it per pair of nets in SPEF.