Function - room (8)
I believe the answer is:
capacity
I believe this is a double definition.
'function' is the first definition.
(I know that capacity is a type of function)
'room' is the second definition.
(thesaurus)
(Other definitions for capacity that I've seen before include "Ability, volume" , "The amount that can be contained, space" , "Capability to perform or produce" , "A city cap has ability to contain" , "Ability to contain or accommadate" .)