According to the definition: the bell-shaped housing covering the clutch and the flywheel in an automobile engine <After installing and torqueing all the bell housing bolts to spec, you can reinstall any motor mounts that you had removed, the drive axles, as well as any other components under the car.
Bell housing is a colloquial/slang term for the portion of the transmission that covers the flywheel and the clutch or torque converter of the transmission on vehicles powered by internal combustion engines. This housing is bolted to the engine block and derives its name from the bell-like shape that its internal components necessitate. The starter motor is usually mounted here, and engages with a ring gear on the flywheel. On the opposite end to the engine is usually bolted to the gearbox. The use of different bell housings on a transmission allows the same transmission to be used on multiple engines in multiple applications. However, on some transmissions, the bell housing is a non-removable part of the transmission case. This is particularly true with front wheel drive transmissions, which are much shorter than conventional rear wheel drive transmissions.