Untrustiest is a word that means someone or something that is not reliable or cannot be trusted. The best antonym for this word is "trustworthy," which means reliable, dependable, and deserving of trust. Other antonyms for untrustiest include "honest," "faithful," "credible," "factual," "truthful," "dependable," "reliable," and "trustful." These words have positive connotations and are used to describe people and things that can be relied upon and are worthy of trust. When used in a sentence, antonyms for untrustiest can help convey a positive impression and ensure that the person or thing being described is trustworthy and reliable.