The antonyms for the word "more confirmable" could vary depending on the context of its use. However, some possible antonyms include uncertain, doubtful, insecure, ambiguous, unconvincing, and unreliable. These words suggest that a piece of information or evidence cannot be confirmed as true or reliable. For instance, "uncertain news" implies that the authenticity of the report is doubtful. Similarly, the term "unreliable evidence" indicates that the evidence cannot be fully trusted. Therefore, the antonyms for "more confirmable" underline the lack of confidence or trust in the accuracy or authenticity of something.