Untrustworthily is an adverb that describes a person or thing that is not reliable or dependable. There are several synonyms that can be used to describe this type of behavior. For instance, dishonestly, unscrupulously, or deceitfully can be used to refer to someone who cannot be trusted. Other synonyms include treacherously, duplicitously, unfaithfully, and disloyally. Each of these words describes a person who cannot be relied upon to keep their word or honor their commitments. It is important to be able to recognize these types of behaviors when dealing with other people to avoid being deceived or taken advantage of.