These are book synonyms but there is not a synonym for book that covers everything the word book covers. Stone is a great synonym for rock. Book doesn't have a synonym that is this great. Text or edition are probably the best synonyms available but they don't work well if you talking about a novel.
You can find book synonyms at Word Hippo, Synonym.com and Thesaurus.com.
Here are some of the synonyms available for book with some explanations of why they are not perfect.
- Bestiary - only works for books about beasts
- Ebook - works only for electronic versions
- Hardback - doesn't work for paperbacks
- Novel - doesn't work for textbooks and non-fiction
- Opuscule - does not work for larger works
- Reference - good synonym for nonfiction but not for fiction
- Tome - doesn't work for small books
- Work - as in the author's latest work