Our name comes from “4 quadrant” control.
The word ‘quadrant’ comes from a graph. The graph below shows the blank on which you might start to draw motor voltage and motor current.
The bottom two quadrants are for reversing.
So a ‘1 quadrant’ drive gives forward drive but no regen braking and no reversing. A 2 quadrant gives forward drive and braking bit np reversing – yes one which gave drive but no braking , with reversing, would also be 2 quadrant, but this is not usually used.
A 4 quadrant drive gives reversing with regenerative braking, thus operating in all 4 quadrants.