"Knock around" is a phrasal verb that can be used in a variety of contexts. It typically means to treat someone or something roughly or to move around aimlessly. Synonyms for this term include words such as rough up, toss around, jostle, shake up, and tumble. These words all convey a sense of rough handling or movement without a clear purpose. "Knock about" is another synonym that specifically refers to aimless movement or travel. In certain contexts, synonyms including toss, throw, or jolt could also be used to describe the same action. Ultimately, the best synonym will depend on the specific context in which "knock around" is being used.