You might consider 'zip cord' a cable
Not in my book it isn't.
Cable in my interpretation of the word, means, individual wires (stranded or solid) insulated with an appropriately rated insulation.
These two insulated conductors are then covered with an outer sheathing of equal voltage rating to the core insulation.
This sort of cable is called Double Insulated over here.
Using Single insulated wire as fixed wiring over here will get you into a LOT of trouble.