a built structure: something raised by construction, seen as a solid measurable object rather than as a home or a defense
Every appearance of this word sits inside Ezekiel's long guided tour of the future temple in chapters 40 to 42, where a man carrying a measuring reed walks the prophet through the complex and calls out dimensions. The word is the plain term for a thing that has been built. It says nothing about who lives there, what it is used for, or how it is decorated. It points at the construction itself, the part you can lay a measuring reed against.
That plainness lets one noun cover two things English usually keeps apart. In Ezekiel 40:5 it names the solid body of the outer wall, measured one reed thick and one reed high, so most English Bibles simply say "wall" at that point. From Ezekiel 41:12 onward it names a large building standing west of the temple, and the guide keeps pointing back to that building to fix where the reader is standing while the side rooms are being measured.
Hebrew had more specific words on hand. A house (בַּיִת) is named for the household inside it, and a city wall (חוֹמָה) is named for what it keeps out. This noun is deliberately blanker than either, which is why the same vision can apply it to a wall's mass in one chapter and to a whole building in the next. Earlier in the same vision Ezekiel reaches for a close relative of it (מִבְנֶה) to describe the city-like shape he sees from the mountaintop.