Why is a nation easy to describe but hard to define?
Nation is an assumption that can sustain or remain as nation i.e. the largest community with the sweet cohesion of nationality i.e. its abstruct form. It is only power that prevents cultural diversity from its conversion into cultural challenges. Mutual trust, support and identification of communities interwoven with it can only give a nation its everlasting existence.
As native is an aspiration of its member communities, it is difficult to define a nation. It is like a breathing air that requires state for its manifestation. There are nations founded on the basis of common cultural, historical and political institutions but it is hard to come up with any defining features i.e. any characteristics that a nation must possess.