The phrase "lash into fury" means to suddenly become extremely angry or agitated. Synonyms for this phrase include "explode in rage," "erupt in anger," "fume with fury," "boil with rage," "seethe with anger," and "fly into a rage." These words convey a sense of intense emotions and the suddenness with which they can erupt. When someone lashes into fury, their behavior can become irrational and unpredictable. It is important to recognize the signs of this kind of anger and to seek help if it starts to become a problem in your life or the lives of those around you.