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
The mega backdoor Roth can be a powerful retirement savings strategy whether you buy a house or not.
From MarketWatch ● Jul. 20, 2026
Broadway has settled into parody mode after suffering some mega collapses.
From Los Angeles Times ● Jul. 15, 2026
Climate rights group Greenpeace Africa called on Tuesday for a halt to a proposed mega oil refinery project by Africa's richest man, Aliko Dangote, in Kenya's coastal region, warning of environmental risks.
From Barron's ● Jul. 14, 2026
Then the New York Times reported that Swift had hired the entirety of Madison Square Gardens for a mega event just before Independence Day weekend.
From BBC ● Jul. 1, 2026
Now, as I watched the mega screen where the roster of names would appear, I felt, deep down, that I could’ve done better.
From "Courage to Soar" by Simone Biles
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.
