The antonyms for the word "un-convincing" are quite straightforward. The first and most obvious opposite would be "convincing." Convincing means something that is convincing and persuasive, whereas un-convincing means the opposite - not convincing or ineffective. Other antonyms could be "persuasive," "credible," "plausible," or "sound." Each of these words implies a sense of believability and strength in argument or presentation, which un-convincing simply does not possess. When looking for antonyms of this word, it is clear that the opposite meanings indicate a high level of persuasiveness and credibility in one's argument or presentation.