There are several synonyms for the phrase "render ineffective". Synonyms for this phrase include neutralize, thwart, undermine, incapacitate, defeat, nullify, counteract, sabotage and impair, among others. Whether in professional or personal contexts, it is sometimes necessary to find a way to render something ineffective. It may be a strategy, plan, or an individual whose actions may require counteractive measures in order to ensure success. Using synonyms such as these can be helpful in avoiding repetition in writing and speech and also shows the variety of ways in which one can express a particular type of message.