gearbox

or gear box

[ geer-boks ]
/ ˈgɪərˌbɒks /

noun

a transmission, as in an automobile.
a shield or housing for gears.

Origin of gearbox

First recorded in 1885–90; gear + box1

British Dictionary definitions for gearbox

gearbox
/ (ˈɡɪəˌbɒks) /

noun

the metal casing within which a train of gears is sealed
this metal casing and its contents, esp in a motor vehicle