Is the word their a noun in sentence twins cannot find new books?

The word "their" in the sentence "Twins cannot find new books" is not a noun. It is a possessive pronoun.

Here's why:

* Nouns are words that name people, places, things, or ideas. In this sentence, the nouns are "twins," "books."

* Pronouns are words that replace nouns. "Their" replaces the noun "twins."

* Possessive pronouns show ownership or belonging. In this case, "their" shows that the twins own or possess the books.

Let me know if you have any other questions!