spoil the effect of; make inoperative; spoil; weaken
Do not take these two medicines at the same time, because the one will vitiate the effect of the other.
vitium (fault, defect, blemish, crime, vice) (Latin)
augment, bolster, buttress, enhance, hone
vitiate is vish + ate, vish in the hindi language means poison. if you make anyone eat poison it's an IMMORAL ACT and the person will be in an IMPERFECT condition.