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
As high-flying technology stocks crashed and the mega- mergers of the late 1990s faded away, Goldman Sachs’s investment-banking revenue plunged to $2.71 billion in 2003 from $5.37 billion in 2000.
From BusinessWeek ● Jul. 22, 2011
Four of the men were shouting something through mega- phones.
From "Kaffir Boy: An Autobiography" by Mark Mathabane
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
And it’s not by accident that coastal habitats are aggressively protected and most of the shoreline is free of mega resorts and architectural clutter.
From Los Angeles Times ● Jul. 11, 2026
South Korean chip giant SK hynix is expected on Thursday to set the price for its mega US listing that could be one of the world's largest stock sales.
From Barron's ● Jul. 9, 2026
Wall Street has nevertheless been galvanized by recent mega awards that were even bigger than the salami win.
From The Wall Street Journal ● Jun. 30, 2026
“Like, I’m pretty sure NYU is mega gay.”
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.
