"Cry uncle" is an idiom that means to admit defeat or surrender. It is often used in situations where someone is unwilling to give up, but is ultimately forced to do so. There are several synonyms that can be used instead of "cry uncle," including "throw in the towel," "give up the ghost," and "wave the white flag." Each of these expressions conveys a similar sense of admitting defeat or surrendering, but with slightly different connotations. For instance, "throw in the towel" suggests a sense of exhaustion, while "wave the white flag" suggests a literal surrender. Ultimately, all of these synonyms are effective ways of expressing the idea of giving up.