The term "unfallacious" refers to something that is free from errors, misconceptions, or false assumptions. There are several other synonyms for the word, including "accurate," "correct," "true," "valid," "precise," "authentic," "trustworthy," and "reliable." Each of these words can be used in different contexts depending on the intended meaning. For instance, "accurate" may be appropriate when describing a measured value whereas "reliable" may be used when discussing the consistency of a process or result. In any case, the use of any of these words can help communicate a sense of reliability and trustworthiness to one's audience.