V1 is the “takeoff decision speed” (roughly as you describe). Vr is the speed at which rotation occurs. Vmu is the “minimum unstick” speed (the lowest speed at

V1 is the “takeoff decision speed” (roughly as you describe). Vr is the speed at which rotation occurs. Vmu is the “minimum unstick” speed (the lowest speed at which liftoff is possible). V2 is the takeoff safety speed, which is faster than liftoff speed, and the minimum target speed for initial climb.