missive
Pronunciation: /ˈmɪsɪv/
noun
often humorous- a letter, especially a long or official one: yet another missive from the Foreign Office
- Scots Law a document in the form of a letter exchanged by the parties to a contract. See also conclude missives at conclude.
Origin:
late Middle English (as an adjective, originally in the phrase letter missive): from medieval Latin missivus, from Latin mittere 'send'. The current sense dates from the early 16th century