mis·sive
noun/ˈmɪsɪv/
/ˈmɪsɪv/
(formal or humorous)- a letter, especially a long or an official one
信函；（尤指）长信，公函 Word Originlate 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 cent.