antioxidant vs inhibitor

antioxidant and inhibitor both are nouns.

Word	Noun	Adjective	Verb	Adverb
antioxidant	Yes	No	No	No
inhibitor	Yes	No	No	No

As nouns, inhibitor is a hypernym of antioxidant; that is, inhibitor is a word with a broader meaning than antioxidant:

antioxidant: substance that inhibits oxidation or inhibits reactions promoted by oxygen or peroxides
inhibitor: a substance that retards or stops an activity

antioxidant (noun)	inhibitor (noun)
substance that inhibits oxidation or inhibits reactions promoted by oxygen or peroxides	a substance that retards or stops an activity