- mega-
- prefix, often meaning "large, great," but in precise scientific language "one million" (megaton, megawatt, etc.), from Gk. megas "great, large, mighty" (fem. megale), from PIE *meg- "great" (cf. L. magnus, Goth. mikils, O.E. micel; see mickle). Mega began to be used alone as an adj. 1982.
"High-speed computer stores 2.5 megabits" [headline in "Electronics" magazine, Oct. 1, 1957]