booster vs dosage

booster and dosage both are nouns.

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

As nouns, dosage is a hypernym of booster; that is, dosage is a word with a broader meaning than booster:

Other hypernyms of booster include dose.

booster (noun)	dosage (noun)
an additional dose that makes sure the first dose was effective	a measured portion of medicine taken at any one time
the first stage of a multistage rocket	the quantity of an active agent (substance or radiation) taken in or absorbed at any one time
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.