master cylinder

English Thesaurus

1. a cylinder that contains brake fluid that is compressed by a piston (noun.artifact)

hypernym	:	cylinder, piston chamber,
definition	:	a chamber within which piston moves (noun.artifact)

part meronym	:	hydraulic brake, hydraulic brakes,
definition	:	brake system in which a brake pedal moves a piston in the master cylinder; brake fluid then applies great force to the brake pads or shoes (noun.artifact)