hot rod vs automobile

hot rod and automobile both are nouns.

Word	Noun	Adjective	Verb	Adverb
hot rod	Yes	No	No	No
automobile	Yes	No	Yes	No

As nouns, automobile is a hypernym of hot rod; that is, automobile is a word with a broader meaning than hot rod:

hot rod: a car modified to increase its speed and acceleration
automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of hot rod include auto, car, machine, motorcar.

hot rod (noun)	automobile (noun)
a car modified to increase its speed and acceleration	a motor vehicle with four wheels; usually propelled by an internal combustion engine

hot rod (verb)	automobile (verb)
	travel in an automobile