The phrase "were one's case" is not a word with antonyms, as it is a complete phrase that means "to be one's argument or situation." However, some of the words in this phrase do have antonyms. The word "were," which is the past tense of "be," has the antonym "weren't," which is a contraction for "were not." The word "one," referring to a single person or entity, has the antonym "many," meaning a large number of people or things. The word "case," meaning an argument or legal matter, has the antonym "agreement," meaning a resolution or compromise between two parties. While "were one's case" does not have a direct antonym, understanding the antonyms of its component words can help clarify its meaning.