"Mulling something over" is a common phrase used to describe the act of contemplating or considering a thought or idea. However, there are various synonyms that can also be used to express this same sentiment. One such synonym is "pondering," which implies deep thought or reflection. "Ruminating" is another word that can be used to describe the process of thinking things over in a slow and deliberate manner. "Reflecting" and "meditating" are also great alternatives to "mulling something over," as they suggest a deeper level of introspection. No matter which synonym is used, the important thing is to take the time to consider things carefully before making any decisions.