Is the a common noun or pronoun?

The Word 'the' is not a noun or a pronoun.

The Word 'the' is the definitearticle. The definite article 'the' is placed before a noun to indicate that the noun is a specific person (persons) or thing (things).

The indefinite articles (a and an) are placed before a singular noun to indicate that the noun is a Word for any person or thing.