brake cylinder vs cylinder

brake cylinder and cylinder both are nouns.

Word	Noun	Adjective	Verb	Adverb
brake cylinder	Yes	No	No	No
cylinder	Yes	No	No	No

As nouns, cylinder is a hypernym of brake cylinder; that is, cylinder is a word with a broader meaning than brake cylinder:

brake cylinder: a cylinder that contains brake fluid that is compressed by a piston
cylinder: a chamber within which piston moves

Other hypernyms of brake cylinder include piston chamber.

brake cylinder (noun)	cylinder (noun)
a cylinder that contains brake fluid that is compressed by a piston	a cylindrical container for oxygen or compressed air
	a chamber within which piston moves
	a surface generated by rotating a parallel line around a fixed line
	a solid bounded by a cylindrical surface and two parallel planes (the bases)