Wordnet 3.0
NOUN (1)
1.
the shell (metal casing) in which a train of gears is sealed;
[syn: gearbox, gear box, gear case]
WordNet (r) 3.0 (2006):
gear box
n 1: the shell (metal casing) in which a train of gears is
sealed [syn: gearbox, gear box, gear case]