Loosely put a book is reading material but so are magazines and e - articles. A tome is a word meaning large book.
"That book is mine." ="It is my book."
There are no adjectives or adverbs. The word 'a' is an article, not actually an adjective. The sentence "I have recently written a biographical book", for example, would have the adverb 'recently' (when was it written) and the adjective 'biographical' (what kind of book).
The adjective in the sentence is "mystic," as it describes the type of horse in Pedro's favorite book.
Noun
The word 'book' is a noun, a verb, and an adjective.The adjective 'book' describes a noun as relating or pertaining to books (book salesman); knowledge learned from books rather than actual experience (book education); shown on a ledger (book assets).
The word 'this" in the sentence is an adjective describing book.
A demonstrative pronoun replaces a noun, while a demonstrative adjective modifies a noun. For example, in the sentence "This is my book," "this" is a demonstrative pronoun replacing the noun "book," and in the sentence "I want that book," "that" is a demonstrative adjective modifying the noun "book."
There is no actual adjective in the sentence. The noun "math" (mathematics) comes before the noun "book" but this is called a noun adjunct or attributive noun, rather than an adjective, which would describe a characteristic of the book (large, new, thick).
Adjective a+
A possessive pronoun functions as an adjective when it modifies a noun, indicating ownership or relationship. For example, in the phrase "her book," "her" is a possessive pronoun acting as an adjective because it describes the noun "book." If the pronoun stands alone without a noun (e.g., "That book is hers"), it is functioning as a possessive pronoun, not as an adjective.
In the sentence "Her book is on the table," the word "her" is the possessive pronoun being used as an adjective to describe the noun "book."
Reading can be a verb a noun or adjective. verb -- I am reading a good book. noun -- I like reading. adjective -- Have you seen my reading glasses?