Next-door means living or being in the building immediately beside. The next-door neighbour.
It is hyphenated as an adjective and written as two words after the verb. A next-door neighbour is the person you are most likely to need and least likely to know.
1adjectivenext-doorLiving or being in the building immediately beside.
“The next-door garden was three feet higher than theirs.”
next-door is a quality.