The antonyms for the word "wert valid" are numerous, as it is a term that signifies something that is truthful or legally binding. Words that are opposite in meaning to "valid" include invalid, void, illegal, unsound, false, ineffective, unreasonable, and unfounded. When something is invalid, it lacks credibility or authority, and does not hold up under scrutiny. A void contract, for instance, is one that is deemed unenforceable because it is in violation of the law. An unsound argument is one that is flawed or illogical, and cannot be defended with evidence. By understanding these antonyms for "valid," individuals can better assess the legitimacy of claims and actions.