(1) Million (10 to the 6th power). Abbreviated "M". In communications, mega typically refers to 1,000,000. In storage, mega typically refers to 1,048,576. See MB, binary values and space/time.

(2) A prefix attached to words that means a very large size or quantity. For example, "megabucks" means a lot of money. See giga.

(3) (MEGA) A personal computer series from Atari that was Motorola 68000 based, ran under GEM and the TOS operating system and included a MIDI interface. It was ST compatible.