As "un-truer" indicates the negation or reversal of truth, its opposite term would signify the state of being truthful or reliable. Some antonyms for "un-truer" that convey this meaning are genuine, valid, accurate, sincere, trustworthy, honest, and credible. The antonyms of "un-truer" could also encompass the idea of authenticity or genuineness, such as reliable, dependable or bona fide. Using these antonyms, we can infer that if something is un-truer, it is untrue, fake or deceitful, while the antonyms of un-truer refer to something that is true, real or honest. In sum, the antonyms of un-truer are concepts that revolve around the idea of genuine, reliable or honest expression.