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• micro
  micro

  adjective

  extremely small.
• micro-
  micro-

  a combining form with the meanings “small” (microcosm; microgamete ), “very small in comparison with others of its kind” (microcassette; microlith ), “too small to be seen by the unaided eye” (microfossil; microorganism ), “dealing with extremely minute organisms, organic structures, or quantities of a substance” (microdissection; microscope ), “localized, restricted in scope or area” (microburst; microhabitat ), “(of a discipline) focusing on a restricted area” (microeconomics ), “containing or dealing with texts that require enlargement to be read” (microfilm; microreader ), “one millionth” (microgram ).
• micro–
  micro–

  A prefix that means: “small” (as in microorganism) or “one millionth” (as in microsecond).

micro

¹ American  

[mahy-kroh] / ˈmaɪ kroʊ /

adjective

1. extremely small.

2. minute in scope or capability.

3. of or relating to microcomputers.

4. of or relating to microeconomics.

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noun

• micros
  plural

1. anything extremely small in scope or capability.

2. a microcomputer.

3. microeconomics.

micro- ² American  

especially before a vowel, micr-.

1. a combining form with the meanings “small” (microcosm; microgamete ), “very small in comparison with others of its kind” (microcassette; microlith ), “too small to be seen by the unaided eye” (microfossil; microorganism ), “dealing with extremely minute organisms, organic structures, or quantities of a substance” (microdissection; microscope ), “localized, restricted in scope or area” (microburst; microhabitat ), “(of a discipline) focusing on a restricted area” (microeconomics ), “containing or dealing with texts that require enlargement to be read” (microfilm; microreader ), “one millionth” (microgram ).

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micro ¹ British  

/ ˈmaɪkrəʊ /

adjective

1. very small

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noun

1. short for microcomputer microlepidoptera microprocessor microwave oven

micro- ² British  

combining form

1. small or minute

   microspore

2. involving the use of a microscope

   micrography

3. indicating a method or instrument for dealing with small quantities

   micrometer

4. (in pathology) indicating abnormal smallness or underdevelopment Compare macro-

   microcephaly

   microcyte

5. μ. denoting 10 ^–6

   microsecond

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micro– Scientific  

1. A prefix that means: “small” (as in microorganism) or “one millionth” (as in microsecond).

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Usage

What does micro- mean? Micro- is a combining form used like a prefix meaning “small.” In units of measurement, micro- means "one millionth." The form micro- is often used in a variety of scientific and technical terms. Micro- comes from Greek mīkrós, meaning “small.” The Latin equivalent of mīkrós is parvus, also meaning “small,” which is the source of terms such as parvovirus, a type of virus with a name that literally means “small poison.” To learn more, check out our entry for parvovirus. What are variants of micro-?When combined with words or word elements that begin with a vowel, micro- becomes micr-, as in micrify, which comes from the Latin equivalent of the form. Want to know more? Read our Words That Use article about micr-.

Other Word Forms

Noun Inflected Forms

• micros
  plural

Etymology

Origin of micro¹

Independent use of micro-, or shortening of words with this initial element

Origin of micro-²

< Greek: combining form representing mīkrós small

Explanation

Micro things are so small you can't see them, or reduced to a very small scale. When you study a subject like economics on a micro level, you look at individual markets instead of the whole economy. Most topics can be discussed or studied on a micro level — up close, looking at separate examples — or a macro level, stepping back to view the larger, wider picture. A change in climate is hard to see on the micro level (your state may have had a particularly cold winter), but easier on a macro level (the average temperature may still have increased over the last 100 years). Micro comes from the Greek mikros, "small."

Example Sentences

See Examples For:

micro micro- micros

They include aspiring uranium suppliers as well as small, advanced and micro reactor, or SAMR, developers, nuclear-reactor supply chain firms and investors, he said.

From The Wall Street Journal ● Sep. 10, 2026

The work could also support the development of next-generation high-reliability micro energy systems and self-powered sensing technologies.

From Science Daily ● Aug. 31, 2026

Instead, “American Doctor” focuses on the micro, giving voice to the doctors and caregivers who traditionally have been spared during armed conflicts, as laid out by the Geneva Conventions.

From Los Angeles Times ● Aug. 21, 2026

"I say it's micro power, so we have to think about what micro power can do," he said.

From Barron's ● Aug. 5, 2026

This one happened to be an economist who, instead of thinking grand macro thoughts, favored his own list of offbeat micro curiosities.

From "Freakonomics: A Rogue Economist Explores the Hidden Side of Everything" by Steven D. Levitt

“That’s their worldview, and navigating life as a Black woman, you’re going to experience micro- and macroaggressions,” she says.

From MarketWatch ● Feb. 28, 2026

Then a short lesson in micro- and macroeconomics:

From The Wall Street Journal ● Jan. 23, 2026

They used this relationship between micro- and macro-scale deformation to develop a new model for how glaciers flow.

From Science Daily ● Jun. 3, 2024

Yes, they’re cheap and convenient, but like a raccoon that crashes your dinner party, they get into everything: our rivers and oceans, and even our bloodstream, in the form of micro- and nano-plastics.

From Seattle Times ● Apr. 19, 2024

Dona Amelia is onstage, in the spotlight, talking into the micro- phone.

From "The Queen of Water" by Laura Resau

“Too many people are focusing on the micros, and not the macros in life,” the comedian and radio host said in a statement.

From Seattle Times ● Feb. 29, 2024

"All industries are doing very well from micros up to corporates. I can't think of any industry which this year has problems."

From Reuters ● Nov. 5, 2022

“We use it for our dishes here at the bistro and for our events. They’re clean, they have good taste. I like to have micros with bigger stems and he does that.”

From Washington Times ● Jul. 23, 2022

“Alongside the top-line perspective he held, he was able to still make time for the important micros of life.”

From New York Times ● Dec. 2, 2021

Much hacking on small, non-MMU micros used to consist of `peek'ing around memory, more or less at random, to find the location where the system keeps interesting stuff.

From The Jargon File, Version 4.2.2, 20 Aug 2000 by Guy L. Steele

Related Words

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