The person who used to be, but is no longer your next door neighbor.
I invited my ex-door neighbor from California; I hope you don't mind.
by Jeul June 27, 2007
The person who used to live next door to you, but no longer does, either because they moved away or you did.
Susie just moved away, I guess that makes her my ex-door neighbor.
by Zekk1331 October 03, 2011