Being untruthful, or deceitful, can have serious consequences in personal and professional relationships. However, there are antonyms to this negative trait that can improve communication and foster trust. One antonym is honesty, which involves telling the truth even when it is difficult or unpopular. Another antonym is authenticity, which means being true to oneself and expressing genuine thoughts and feelings. Transparency is another antonym, which involves being open and sharing information freely. Trustworthiness is also an antonym for being untruthful, which involves being reliable and keeping one's promises. These traits can lead to stronger relationships, better decision-making, and a more positive reputation.