The word 'un-believable' can be described as something that is hard or impossible to believe. Its antonyms are the words believable, credible, and plausible, which imply that something is believable or trustworthy. Other antonyms for 'un-believable' include probable, conceivable, and acceptable. These words suggest that something is logical, reasonable, and can be accepted or believed. Similarly, trustworthy, reliable, and convincing are also antonyms to 'un-believable,' implying that something is reliable, based on facts or evidence, and can be trusted. These words offer a sense of credibility and openness, allowing individuals to express their thoughts and ideas with confidence.