mega-

(M-)

   1. a metric prefix meaning 10⁶, or one million. (The form meg- is often used before a vowel, as in megohm for one million ohms.) The prefix is also common in ordinary language, meaning "very large," as in megabucks or megadose. The prefix is derived from the Greek word for large, megas.

   2. in measuring the storage capacity of a computer, the prefix mega- often means 2²⁰ = 1 048 576 instead of an even one million. By a 1998 resolution of the International Electrotechnical Commission, the new prefix mebi- (Mi-) is supposed to replace mega- for 2²⁰.