mega

Prefix mega- (originally) Very large, great. In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by one million (1,000,000.) SI Symbol: M. (computing) Multiplying the unit to which it is attached by 220 (= 1,048,576, the binary number closest to a million). Computing symbol: Mi. (computing, marketing) Multiplying the unit to which it is attached by 210 × 103 (= 1,024,000, the binary round number closest to a million). (slang, augmentative) Really, very, uber-, super-.