"Truthlessness" is a word that describes the state of not adhering to truth or a lack of sincerity. There are many synonyms that can be used in place of this word, including dishonesty, deceit, falsehood, insincerity, and fabrication. These words all share a common theme of not being truthful or lacking honesty. They are often used to describe situations or individuals that are seen as untrustworthy or unreliable. It is important to use these words carefully as they can have a strong impact on how a person is perceived. In certain contexts, synonyms for "truthlessness" can be helpful in communicating a message, but it is always important to use them judiciously.