protagonist vs booster

protagonist and booster both are nouns.

Word	Noun	Adjective	Verb	Adverb
protagonist	Yes	No	No	No
booster	Yes	No	No	No

As nouns, protagonist and booster are synonyms defined as:

Other synonyms of protagonist include admirer, champion, friend, supporter.

protagonist (noun)	booster (noun)
a person who backs a politician or a team etc.	an additional dose that makes sure the first dose was effective
the principal character in a work of fiction	the first stage of a multistage rocket
	an amplifier for restoring the strength of a transmitted signal
	a thief who steals goods that are in a store
	someone who is an active supporter and advocate
	a person who backs a politician or a team etc.