The phrase "talk down" means to speak condescendingly or patronizingly towards someone. If you are looking for synonyms for this phrase, there are several words and phrases you could use. For instance, you could say that someone is "condescending" or "patronizing" toward others. Alternatively, someone could be described as "belittling" or "disparaging" towards someone else. Other ways to describe this behavior include saying that someone is "talking down to" someone else, or that they are "being haughty" or "contemptuous" towards someone. Ultimately, there are many ways to describe this type of behavior, which can be both frustrating and demoralizing for those on the receiving end.