The term "abandon back" can be interpreted in a few different ways, depending on the context in which it's used. If it's meant to describe leaving something behind or giving up on a task or goal, synonyms might include "relinquish," "forsake," "desert," or "abdicate." If the phrase refers to physically moving away from a particular location, other possible synonyms might include "retreat," "depart," "withdraw," or "evacuate." There are also a range of more colloquial expressions that could be used in conversation or informal writing, such as "beat a hasty retreat," "take off," or "make a run for it".