The antonyms for the word "are untruthful" include honest, truthful, candid, sincere, genuine, reliable, and authentic. These adjectives describe individuals who are frank and straightforward in their communications, and who avoid deception and falsehoods in their interactions with others. They are trustworthy and earnest, and are often admired for their integrity and genuineness. People who are untruthful, on the other hand, are often regarded with suspicion and distrust. In interpersonal relationships, being truthful is essential for building trust and mutual respect, while dishonesty can erode trust and breed resentment. Therefore, it's essential to avoid the temptation to be untruthful and embrace honesty and candor in our interactions with others.