Refer to figure.
V₂ take-off safety speed, or the speed at the screen height, with the critical engine inoperative. This speed cannot be lower than V_MC, otherwise it would be impossible to control the airplane when the critical engine suddenly becomes inoperative with the remaining engine(s) at take-off thrust.

V_MCG is the minimum speed on the ground at which the take-off can be safely continued, when the critical engine suddenly becomes inoperative with the remaining engine(s) at take-off thrust.

V₁ is defined as being the maximum speed at which the pilot must take the first action in order to stop the airplane within the remaining accelerate-stop distance.

V₁ cannot be allowed to be less than V_MCG because engine failure below V_MCG means the airplane is uncontrollable and the definition of V₁ is that the take-off can be continued following engine failure.

Rotation speed, V_R, is the speed at which the pilot initiates action to raise the nose gear off the ground, with the intention of becoming airborne. V_R may not be less then decision speed V₁.

V_MBE is the maximum speed on the ground from which an airplane can safely stop within the energy capabilities of the brakes. V₁ must not be greater than V_MBE. At V₁ the airplane must be able to stop or continue the take-off, but above V_MBE it is impossible to bring the airplane safely to a stop.