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-.
Origin of micro-
< Greek: combining form representing mīkrós small
Can be confusedmacro- micro-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for micro-
small or minutemicrospore
involving the use of a microscopemicrography
indicating a method or instrument for dealing with small quantitiesmicrometer
(in pathology) indicating abnormal smallness or underdevelopmentmicrocephaly; microcyte Compare macro- (def. 2)
denoting 10 –6microsecond Symbol: μ
Word Origin for micro-
from Greek mikros small
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medicine definitions for micro-
Requiring or involving microscopy:microsurgery.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Science definitions for micro-
A prefix that means: small (as in microorganism) or one millionth (as in microsecond).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.