The opposite of "un-trustworthy" is "trustworthy," which means reliable and dependable. It refers to someone or something that can be trusted without hesitation or doubt. Such individuals are known for their honesty and integrity, and they always fulfill their commitments. Furthermore, they are upfront and transparent in their dealings, and they don't hide anything from anyone. Trustworthy people are highly valued and respected in society, and they inspire confidence and faith in others. Moreover, "reliable," "dependable," "authentic," "honest," "credible," and "faithful" are some synonyms for "trustworthy," which present a positive and trustworthy image.