The word classic means something that is a perfect example of a particular style, something of lasting worth or with a timeless quality. The word can be an adjective

Adjective

In grammar, an adjective is a 'describing' word; the main syntactic role of which is to qualify a noun or noun phrase, giving more information about the object signified....

 (a classic car) or a noun

Noun

In linguistics, a noun is a member of a large, open lexical category whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition .Lexical categories are defined in terms of how their members combine with other kinds of...

 (a classic of English literature). It denotes a particular quality in art, architecture, literature and other cultural artifacts. In commerce, products are named 'classic' to denote a long standing popular version or model, to distinguish it from a newer variety.