There are several synonyms for the phrase "talk down to" that are commonly used in English. Some of the most popular alternatives include "condescend," "patronize," "belittle," "undermine," and "debase." Each of these terms implies a level of superiority or condescension, where the speaker is talking down to the listener and implying that they are inferior in some way. If you want to avoid using the phrase "talk down to" in your writing or conversation, consider using one of these synonyms to convey the same idea in a different way. Remember, the most important thing is to communicate your thoughts and ideas clearly and effectively, without resorting to aggressive or dismissive language.