When it comes to finding synonyms for "be proof against," there are several options that can convey a similar meaning. For example, one could use the phrase "be impervious to" to describe something that is resistant to damage or harm. Another option might be to say that something is "immune to" a certain threat or danger. Similar phrases like "resilient to," "unaffected by," or "invulnerable to" can also be used to describe the idea of being proof against something. Overall, there are many ways to express the concept of being resistant to harm or danger, and choosing the right words can help to convey a message with clarity and precision.