What is definition of liu?

I'm sorry, but I need more context to provide a definitive answer to your question. "Liu" is a surname that is commonly found in China and other Asian countries. It can also refer to people, places, organizations, or even products that are named after someone with that last name. Without further context, it's difficult to provide a specific definition of "liu." Please provide more information about the context you are asking about so I can assist you better.