Message-digest function / noun C [18] program function that processes a message to produce a number called a message-authentication code. This number is then used to make a message tamper proof.
Message-integrity scheme / noun C [18] a system that allows the receiver of a message
mkdlr / noun U [6] a Unix and MS-DOS command for creating a directory
MO / adj [19] abbrevlation for magneto-optical. Used to describe storage devices that use a combination of magnetism and laser light.