friend vs exponent

friend and exponent both are nouns.

Word	Noun	Adjective	Verb	Adverb
friend	Yes	No	No	No
exponent	Yes	No	No	No

As nouns, exponent is a hypernym of friend; that is, exponent is a word with a broader meaning than friend:

Other hypernyms of friend include advocate, advocator, proponent.

friend (noun)	exponent (noun)
a person you know well and regard with affection and trust	a mathematical notation indicating the number of times a quantity is multiplied by itself
a person with whom you are acquainted	a person who pleads for a cause or propounds an idea
an associate who provides cooperation or assistance	someone who expounds and interprets or explains
a person who backs a politician or a team etc.