Ex-cathedra is a Latin expression that means "from the chair" or "with authority," referring to a statement made by someone in a position of power or expertise. Some antonyms of ex-cathedra can include uncertified, unaccredited, informal, unverified, and unofficial. These terms reflect a lack of official or recognized authority, and imply a certain degree of ambiguity or uncertainty. Other antonyms could include hesitant, tentative, uncertain, or speculative, which suggest the speaker is expressing an opinion rather than a definitive statement. These antonyms highlight the importance of considering the context and source of any statement, and the need to weigh the credibility and validity of information before accepting it as true.