General:
* Void: A complete absence of anything.
* Vacancy: A state of being unoccupied or empty.
* Hollow: A feeling of emptiness or lack of substance.
* Blankness: A state of being without content or meaning.
* Desolation: A state of complete emptiness or despair.
Emotional:
* Loneliness: A feeling of emptiness and isolation.
* Devoid: Completely lacking in something.
* Deprivation: A lack of something necessary or desirable.
* Yearning: A deep desire for something that is missing.
* Apathy: A lack of interest or emotion.
Physical:
* Vacuum: A completely empty space.
* Space: An empty area or region.
Figurative:
* Nothingness: A state of being non-existent.
* Abyss: A deep, bottomless pit that represents emptiness or despair.
The best word to use will depend on the specific context and the feeling you want to convey.