mega-

1. variant of megalo- ( megalith ); also the initial element in units of measure that are equal to one million of the units denoted by the base word ( megahertz ). : M

mega-

¹

combining_form

1. denoting 10 ⁶ M

   megawatt

2. (in computer technology) denoting 2 ²⁰(1 048 576)

   megabyte

3. large or great

   megalith

4. informal.
   great in importance or amount

   megastar

mega

²

/ ˈmɛɡə /

adjective

1. slang.
   extremely good, great, or successful

mega–

1. A prefix that means:
2. Large, as in megadose, a large dose.
3. One million, as in megahertz, one million hertz.
4. 2 ²⁰ (that is, 1,048,576), which is the power of 2 closest to a million, as in megabyte.

Word History and Origins

Origin of mega-¹

Combining form representing Greek mégas large, great

Word History and Origins

Origin of mega-¹

from Greek megas huge, powerful

Origin of mega-²

C20: probably independent use of mega-

Example Sentences

This mystery winner was part of an incredibly rare draw for the Mega Millions lottery.

From Los Angeles Times

Becker couldn’t say exactly how rare an occurrence that is, but she noted that Mega Millions is a multistate game, and California alone has 23,000-plus retailers who sell tickets.

From Los Angeles Times

In December of last year, they bought one of two winning Mega Millions tickets at a Chevron gas station in Encino, and now they are owed $197.5 million in lottery dough.

From Los Angeles Times

Sam Altman, the chief executive of OpenAI, described him as a “mega hero.”

From New York Times

Sam Altman, the chief executive of OpenAI, called him a “mega hero.”

From New York Times

Related Words

• commanding
• grand
• grandiose
• imperial
• magnificent
• massive
• monumental
• noble
• ominous
• stately
• striking
• towering

Words That Use Mega-

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.

Examples of mega-

A word you may have encountered that features the combining form mega- is megalith, “a stone of great size, especially in ancient construction work, as the Cyclopean masonry, or in prehistoric Neolithic remains, as dolmens or menhirs.” Some of the most well-known megaliths in the world can be found at Stonehenge.

The mega- part of the word means “large,” as we know. The second part of the word, -lith, means “stone,” from the Greek líthos. Megalith literally translates to “large stone.”

What are some words that use the combining form mega-?

• megabacterium
• megabit
• megabyte
• megacephaly
• megachurch
• megacity
• megadeath
• megadont
• megaesophagus
• megafauna
• megaflop
• megagamete
• megahertz
• megahit
• megajoule
• megakaryocyte
• megalitre
• megapixel
• megaplex
• megaphyll
• megaparsec
• megapolis
• megascopic
• megasporangium
• megastructure
• megaton
• megavolt

What are some other forms that mega- may be commonly confused with?

• macro-
• neg-

Not every word that begins with the exact letters mega- or meg- is necessarily using the combining form mega- to denote “large,” e.g., megillah, megilp, or megass. Learn where these words come from and what they mean at our entries.

Break it down!

The combining form -phyll means “leaf.” What does megaphyll, which ferns and seed plants produce, literally translate to?