1. Epistle
2. Correspondence
3. Missive
4. Dispatch
5. Communique
6. Communication
7. Note
8. Memorandum
9. Document
10. Manifesto
11. Circular
12. Pamphlet
13. Bulletin
14. Gazette
15. Script
16. Manuscript
17. Encyclopedia
18. Tome
19. Alphabet
20. Alphabetical
21. Diploma
22. Credential
23. Licence
24. Permit
25. Writ
26. Edict
27. Mandate
28. Rescript
29. Decree
30. Edification

When searching for another word for letter, it is important to consider the context of the situation. Depending on the purpose of the letter, the best ideas for synonyms can vary. For example, if the letter is a formal document, then words such as epistle, correspondence, missive, and dispatch may be the most appropriate. For a more casual letter, words such as note, memorandum, document, manifesto, or circular may be best. If the letter is a written record, then script, manuscript, encyclopedia, or tome may be the best choice. For a brief or short letter, words such as alphabet, alphabetical, diploma, credential, licence, permit, writ, edict, mandate, rescript, or decree may be the most suitable. Ultimately, when searching for synonyms for the word letter, it is important to consider the context and purpose of the letter to find the best ideas.