Define "Kind"

Since the term "kinds" isn't used by scientists it isn't really up to them to define it. Usually the people using a word or term explain what they mean by it when asked. This is what's called "defining" it. Anyway, would you accept scientists' definition of kinds? Why would scientists spend time working on a concept for YECs when YECs won't define what the concept is? And why would they waste time on it when, in all probability, it will be rejected anyway, on the basis that scientists don't take it seriously?