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 ).
Also, especially before a vowel, micr-.

< Greek: combining form representing mīkrós small

macro-, micro-.
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World English Dictionary
micro- or micr-
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.  Compare macro- (in pathology) indicating abnormal smallness or underdevelopment: microcephaly; microcyte
5.  μ denoting 10--6: microsecond
[from Greek mikros small]
micr- or micr-
combining form
[from Greek mikros small]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

comb. form of Gk. mikros "small" (see mica).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

micro- or micr-

  1. Small: microblast.

  2. Abnormally small: microcephaly.

  3. Requiring or involving microscopy: microsurgery.

  4. Symbol μ One-millionth (10-6): microliter.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
A prefix that means: "small" (as in microorganism) or "one millionth" (as in microsecond).
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Related Words
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