Confirmed means something that is established or verified, often through substantial evidence or credible sources. Hence, the antonyms of unconfirmed would be confirmed, ratified, validated, substantiated, supported, endorsed or authenticated. These words are often used in such cases where an individual or an organization needs to ensure the authenticity of a fact or data. For instance, a confirmed reservation ensures that the booking is guaranteed, while an unconfirmed booking may not be viable. The usage of antonyms of unconfirmed ensures reliability, trust and confidence in the information provided, as it has been established positively by reliable sources.