Dark dart is a phrase that refers to an object or action that is sinister or secretive. There are several synonyms that can be used instead of this phrase depending on the context. For instance, "stealthy dart" can be used to describe a secretive action or movement. "Obscure dart" can be used when referring to something that is difficult to understand or mysterious. "Malevolent dart" can be used to describe an action or object that is evil or harmful. "Mysterious dart" is suitable when describing something that is hard to explain or understand. Other synonyms for the phrase "dark dart" include secretive, shadowy, ominous, and enigmatic, among others.