- Also next door. to, at, or in the next house on the street, especially if it is very close by, or the adjacent apartment, office, room, or the like: Go next-door and get your sister. Your sister is next-door. Her brother lives next-door.
- being situated or living next-door: next-door neighbors.
adv.also nextdoor, 1570s, from noun phrase next door “nearest house” (late 15c.), from next + door. Noun meaning “the people living next door” is from 1855.