The term "null void" means having no value or existence. Antonyms for this phrase may include words such as substantial, significant, important, and valid. These words imply the opposite of "null void," indicating that something has meaning, purpose, or weight. For example, a substantial argument is one that has strong evidence and reasoning supporting it. A valid opinion is one that is logical and well-informed. Using antonyms can help clarify ideas and arguments, give emphasis and meaning to a statement, and make it easier for readers or listeners to understand the message being conveyed.