The phrase "strike down" refers to an action taken to invalidate or nullify something. There are numerous synonyms for this phrase, including overturn, reverse, quash, annul, cancel, negate, abolish, nullify, and repeal. Each of these words has its own distinct connotation and usage, but they all convey the idea of undoing or invalidating something that was previously established. For example, a court might strike down a law as unconstitutional, a ruling might be overturned on appeal, or a new policy might be repealed by a subsequent administration. Understanding the nuances of these synonyms and their appropriate usage is important for clear and effective communication.