In the sentence "Both candidates were hopeful," what is the function of "both"?

In the sentence "Both candidates were hopeful," "both" functions as an adjective because it is used to modify the noun "candidates." Adjectives describe or limit nouns, providing additional information about them. In this case, "both" specifies a quantity by indicating that there are two candidates being referred to. This quantitative aspect is a characteristic feature of adjectives.

It is important to note that "both" cannot be classified as a noun because it doesn’t refer to a person, place, thing, or idea on its own. It also does not serve as an adverb, which would modify verbs, adjectives, or other adverbs, nor does it act as a pronoun, which would replace a noun phrase. Thus, the correct identification of "both" as an adjective highlights its role in providing specific information about the noun in the sentence.