Rotten, stale (3)
I believe the answer is:
off
I believe this is a double definition.
'rotten' is the first definition.
(rotten food is 'off')
'stale' is the second definition.
(thesaurus)
(Other definitions for off that I've seen before include "Away, or no longer on the menu perhaps" , "Away, substandard" , "Discontinued" , "Of food, begining to decay" , "Rancid or not in operation" .)