radiator vs radiator cap

radiator and radiator cap both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiator	Yes	No	No	No
radiator cap	Yes	No	No	No

radiator (noun)	radiator cap (noun)
a mechanism consisting of a metal honeycomb through which hot fluids circulate; heat is transferred from the fluid through the honeycomb to the airstream that is created either by the motion of the vehicle or by a fan	cap on the opening in the top of a radiator through which a coolant liquid can be added
heater consisting of a series of pipes for circulating steam or hot water to heat rooms or buildings
any object that radiates energy