The phrase "beat your breasts in sorrow" is an idiomatic expression that means to show excessive grief or remorse for something. It is a figurative way of describing the act of hitting one's chest repeatedly in a show of anguish. There are several synonyms for this expression, including wail, lament, mourn, weep, and grieve. Each of these words highlights the intense feelings of sadness or regret that a person may experience when they are grieving deeply. While these terms may differ slightly in their connotations, they all convey a sense of profound loss and despair that is often associated with difficult emotions.