M. denoting 10 6
megawatt
(in computer technology) denoting 2 20 (1 048 576)
megabyte
large or great
megalith
informal great in importance or amount
megastar
A prefix that means:
Large, as in megadose, a large dose.
One million, as in megahertz, one million hertz.
2 20 (that is, 1,048,576), which is the power of 2 closest to a million, as in megabyte.
What does mega- mean? Mega- is a combining form used like a prefix meaning “large, great, grand, abnormally large.” It is used in many scientific and medical terms. In science, mega- is specifically used as a prefix in units of measure equaling a factor of “one million.” It’s abbreviation is M. So, a megawatt (MW) is one million watts. Mega- comes from the Greek mégas, meaning “large” or “great.”What are variants of mega-?When combined with words or word elements that begin with a vowel, mega- becomes meg-, as in megohm. Mega- is a variant of megalo- and megal-, as in megalomania and megalopsia. Learn more about their specific applications in our Words That Use articles.
Combining form representing Greek mégas large, great
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Beek looked at the yachts around us, mega- and not.
From Los Angeles Times ● May 9, 2023
The West is in a drought so huge that everyone started throwing the prefix mega- in front of it.
From Salon ● Dec. 29, 2021
In fact, the foundation drew contributions from some who were once Clinton’s most bitter GOP enemies, including Newsmax chief executive Christopher Ruddy and conservative mega- donor Richard Mellon Scaife.
From Washington Post ● Jun. 2, 2015
The model in the courtyard is of a never-realized mega- tower by Vladimir Tatlin, with a rotating block for each arm of Soviet power.
From BusinessWeek ● Nov. 3, 2011
Four of the men were shouting something through mega- phones.
From "Kaffir Boy: An Autobiography" by Mark Mathabane
A teenager charged over a small boat Channel crossing was allegedly piloting a "mega dinghy" carrying a record 165 migrants from France to England, the National Crime Agency has said.
From BBC ● Jul. 26, 2026
European banks may not receive quite the same impetus from mega IPOs and the AI capex bonanza as their U.S. counterparts but this is reflected in the significantly lower valuations attached to them.
From MarketWatch ● Jul. 22, 2026
Progressive’s management team—including Andrew Quigg, who took over as CFO this month—must decide what to do with it, and whether to repeat 2025’s mega payout.
From The Wall Street Journal ● Jul. 20, 2026
Broadway has settled into parody mode after suffering some mega collapses.
From Los Angeles Times ● Jul. 15, 2026
A mega close-up selfie of Abby and Simon.
From "Leah on the Offbeat" by Becky Albertalli
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
