Unfaithworthy is a word used to describe someone who is unreliable, disloyal or untrustworthy. There are many other words that can be used to describe someone who lacks loyalty, integrity or trustworthiness. Synonyms for unfaithworthy include unreliable, duplicitous, treacherous, deceitful, untruthful, dishonest, insincere, deceptive, fraudulent, disloyal, and fickle. These words describe a person who cannot be relied on to keep their word or to act with integrity. Whether you are describing a person or a situation, using one of these synonyms can help you accurately convey the sense of distrust and betrayal that comes with someone who is unfaithworthy.