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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

Inflected Forms

noun

• 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

Micro dramas, which are serialised, made-for-mobile clips, have exploded in popularity globally in recent years - but have also drawn criticism for their often sensationalist content.

From BBC • Jun. 5, 2026

Micro dramas have grown into a multi-billion dollar industry for China, attracting large audiences worldwide, including in other parts of Asia and even Africa.

From BBC • Jun. 5, 2026

They’re certainly more likely to sell than PCs with chips from Intel and Advanced Micro Devices.

From The Wall Street Journal • Jun. 2, 2026

Dell’s stock surged after its results, with Super Micro Computer and HPE also seeing boosts.

From The Wall Street Journal • Jun. 1, 2026

In my pocket I had three peach pits from the orchards of Mentana, and four Micro Machine cars to jump over them as if they were boulders.

From "Everything Sad Is Untrue" by Daniel Nayeri

Related Words

• compact
• mini
• pocket
• pocket-size
• portable
• scaled-down
• small