The term "door neighbor" refers to a person who lives next door or in close proximity to someone, often used when describing neighbors that live near each other.
Our next door neighbor who took all the equity out of his house and «invested» in this business scheme only to fail and having to sell his house in a short sale. (esimoney.com)
I bought this years ago at a yard sale from my older next door neighbors who have since past on. (homelovestories.com)
The challenge becomes how are you any different than the problem that your next - door neighbor in the expo hall is trying to solve? (fortune.com)