taxicab vs automobile

taxicab and automobile both are nouns.

Word	Noun	Adjective	Verb	Adverb
taxicab	Yes	No	No	No
automobile	Yes	No	Yes	No

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

taxicab: a car driven by a person whose job is to take passengers where they want to go in exchange for money
automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of taxicab include auto, car, machine, motorcar.

taxicab (noun)	automobile (noun)
a car driven by a person whose job is to take passengers where they want to go in exchange for money	a motor vehicle with four wheels; usually propelled by an internal combustion engine

taxicab (verb)	automobile (verb)
	travel in an automobile