Real Dictionary

MIDI
MIDI is a computer system that allows you to record the output of a musical instrument such as an electric guitar or synthesizer, so that the recording is in a digital form. MIDI is an abbreviation for 'musical instrument digital interface.'

MIDI in American English
an electronic digital system for composing and reproduction, that provides a standard interface connecting electronic musical instruments, such as synthesizers, with computers
adjective: of the length of a midiskirt
noun: a skirt, dress, or coat, of mid-calf length
noun: Musical Instrument Digital Interface: a standard means of sending digitally encoded information about music between electronic devices, as between synthesizers and computers
noun: the south of France

midi in British English
adjective: (of a skirt, coat, etc) reaching to below the knee or midcalf
noun: a generally accepted specification for the external control of electronic musical instruments
noun: the south of France

midi- in American English
of a length to the middle of the calf

midi- in British English
combining form: of medium or middle size, length, etc