booster vs protagonist

booster and protagonist both are nouns.

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

As nouns, booster and protagonist are synonyms defined as:

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

booster (noun)	protagonist (noun)
an additional dose that makes sure the first dose was effective	a person who backs a politician or a team etc.
the first stage of a multistage rocket	the principal character in a work of fiction
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.