next door adjective 2adverb 1preposition 1forms 2 adjective2 •[after a noun] That is in an adjacent place; that is located next door.Try the place next door. •that occupies an adjacent place, especially the building immediately to the left or right adverb1 •In an adjacent building, room or place.He lives next door but one (= two houses from mine). preposition1 •(dialect) Next door to.Next door the kirk was an olden tower, built in the time of the Roman Catholics [...]. — 1932 formsmore next door · most next door