"What is" is a common phrase that is often used in everyday conversation. However, there are many synonyms that can be used to replace this phrase, depending on the context. Some alternatives for this phrase may include "define," "explain," "elucidate," "describe," "clarify," and "convey." Using these synonyms can bring depth and clarity to a conversation or a piece of writing. For instance, instead of asking, "What is the meaning of this book?" you could ask, "Could you define the main message or theme of this book?" This will help the person being asked the question to give a more thoughtful and informative answer.