a written proposal or reminder
"The manager sent a memorandum reminding all staff about the upcoming deadline."
A short note serving as a reminder.
"The manager left a memorandum on my desk to remind me about the meeting tomorrow."
In plain English: A memorandum is an official written message used to share information within a company or organization.
"The manager sent out a memorandum to all employees about the new office hours."
The word entered English as a learned borrowing directly from the Latin phrase memorandum, which is the neuter form of memorandus meaning "to be remembered." It was adopted to describe notes or documents intended for future reference.