(formal memorandum) memo (to somebody) an official note from one person to another in the same organization to write/send/circulate a memo Word Origin early 18th cent.: abbreviation of memorandum.Extra examples A memo on the curriculum changes from the Head of Education. An internal memo about his departure had already circulated. I just posted this memo onto my blog. She circulated a memo to the staff. a government memo obtained by the Associated Press my memo of 28 June, 2001 the contents of a leaked memo The confidential memo was leaked to the press.