reverse gear vs machine

reverse gear and machine both are nouns.

Word	Noun	Adjective	Verb	Adverb
reverse gear	Yes	No	No	No
machine	Yes	No	Yes	No

reverse gear (noun)	machine (noun)
the gears by which the motion of a machine can be reversed	any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of human tasks
	a motor vehicle with four wheels; usually propelled by an internal combustion engine
	a device for overcoming resistance at one point by applying force at some other point
	a group that controls the activities of a political party
	an intricate organization that accomplishes its goals efficiently
	an efficient person

reverse gear (verb)	machine (verb)
	make by machinery
	turn, shape, mold, or otherwise finish by machinery