What is a "meta component" in the context of bootstrap or as a general web design term?

In the documentation for the bootstrap navbar, navbar is described as a "meta component". As far as I can tell, this is the only component described as a "meta component", and I have not been able to find an explanation of this term.

What is a "meta component"? Is it just a throwaway term in the bootstrap documentation, or does it refer to a component with particular characteristics either within bootstrap or in web design in general?