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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

plural

micros

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  

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 ² British  

/ ˈmaɪkrəʊ /

adjective

1. very small

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noun

1. short for microcomputer microlepidoptera microprocessor microwave oven

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-.

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

“I just think our faces are so intricate and the micro expressions are so intricate, so that’s always real,” he said.

From Los Angeles Times • May 13, 2026

The discrepancy between the macro and micro perspectives shows how.

From Slate • May 11, 2026

"There are micro baby-steps of recovery where I take two steps forward and four steps back." he said.

From BBC • May 7, 2026

There’s a difference, though, between erratic behavior on the macro and on the micro level.

From The Wall Street Journal • Apr. 16, 2026

Come now, they always said, and then you arrived to find two people waiting to get micro braids and still the owner would tell you “Wait, my sister is coming to help.”

From "Americanah" by Chimamanda Ngozi Adichie

Related Words

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