When it comes to finding synonyms for the phrase "school dictionary," a few options come to mind. One option is simply "dictionary," as any dictionary can be used by students in the classroom. Another option is "student dictionary," which indicates a dictionary specifically designed for younger students or those learning a new language. A "vocabulary book" is another synonym, as it refers to a book specifically designed to help students build their understanding and use of language. Finally, "reference book" could also be considered a synonym for "school dictionary," as it refers to any type of book designed to provide information to readers.