I think ‘undead’ means
The dead who will not die
What then is the term
For the living who do not live?
Who have no wish to live?
Who see no point in living?
For whom there is no joy in living?
Are they called the ‘unliving’?
–Meena
(Obviously suffering from GOT withdrawal symptoms!)
Millennial Matriarchs 
Is there a word like that….or not applicable for non-GOT population!!
But coming to the more fundamental question of living to unliving… I think most of us go through stages of being most alive to almost non- living….. that’s essential part of living a life, I guess
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