Definitions for vacantness
Random House Webster's College Dictionary
having no contents; empty; void.
having no occupant; unoccupied:
no vacant seats on this train.
not in use:
a vacant warehouse.
lacking in thought or intelligence:
a vacant expression.
not occupied by an incumbent, official, or the like, as a benefice or office.
free from work, business, activity, etc.:
Origin of vacant:
1250–1300; ME < L vacant-, s. of vacāns, prp. of vacāre to be empty