| mega- [MEG uh], meg- (Greek: large, great, big, powerful; a decimal prefix used in the international metric system for measurements).When measuring in the metric [decimal] system, it means a million [U.S.] or millionfold [U.K.]: 106 [1 000 000]. The metric symbol for mega- is M.acromegaly: megabit: megabyte: megacephalic: megacephalous: megacosm: megacurie: megacycle: megadactyl: megadactylia: megadactylism: megadactyly: megaderm: megadont: megadontism: megadyne: megaelectron: megaelectronvoltcurie: megaelectrovolt: megaerg: megaesophagus: megagauss: megagnathia: megagram: megahertz: megajoule: megalgia: megalith: megalopolis: megalosaur: megameter: megaparsec: megaphone: megaphyllous: megapod: megapode: megarad: megascope: megascopic: megasecond: megaseism: megasporophyll: megathere: megatherium: megatherm: megathermophyte: megaton: megavitamis: megavolt: megawatt: megohm: megohmmeter: omega: |