I don't have such a definition. I am adefinitive.
My position is that Christians have a definition with strong rationale that correlates to human history and to Darwin's theory of evolution (although they are typically not aware of this and certainly don't want to emphasize it). The Christian definition of, and view on, marriage is beneficial to society, whereas the WOKE, society-destroying, humanity-HATING position of leftists is destructive to society. As a result, I side with the Christians every time.