"Keep in check" is a phrase that means to control or monitor something in order to prevent it from getting out of hand. There are many synonyms for this phrase, including "restrain," "regulate," "supervise," "moderate," "manage," "monitor," and "control." Other alternatives to the phrase could be "hold back," "curb," "limit," "keep a lid on," "dampen down," or "keep under control." These synonyms can be used in various contexts, including personal relationships, business ventures, or even self-discipline. Overall, using the right synonym for "keep in check" can help convey a message of responsibility and accountability.