There are several synonyms for the phrase "abort a plan" depending on the context in which it is used. One common synonym is "cancel," which implies that the plan was never carried out. Another synonym is "scrub," which is used in the context of aborting a mission or operation. "Terminate" is another synonym, and it suggests that the plan was ended before completion. "Abandon" is another synonym used when a plan or project is given up on. Lastly, "halt" is a synonym that denotes putting an immediate stop to a plan or action. All these synonyms can be used interchangeably, depending on the context and the situation at hand.