[ mahy-kroh ]
See synonyms for: micromicros on Thesaurus.com

  1. extremely small.

  2. minute in scope or capability.

  1. of or relating to microcomputers.

  2. of or relating to microeconomics.

noun,plural mi·cros.
  1. anything extremely small in scope or capability.

  2. a microcomputer.

Origin of micro

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

Other definitions for micro- (2 of 2)


  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).

Origin of micro-

<Greek: combining form representing mīkrós small
  • Also especially before a vowel, micr-.

Words that may be confused with micro-

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use micro in a sentence

  • It is probably caused by two micro-organisms living in symbiosis—one a fusiform bacillus, the other a long spirillum (Fig. 124).

    A Manual of Clinical Diagnosis | James Campbell Todd
  • Upon ulcerated surfaces it is often mingled with other spiral micro-organisms, which adds to the difficulty of its detection.

    A Manual of Clinical Diagnosis | James Campbell Todd
  • He watched as Arnold conferred with a group of his techs about a micro-chron, and the time was carefully noted for Central Record.

    We're Friends, Now | Henry Hasse
  • Albert selected all the incriminating letters and documents he could find and packed the micro-files in his jacket.

    Insidekick | Jesse Franklin Bone
  • Pathological micro-organisms have very complicated products which are in large part poisonous.

British Dictionary definitions for micro (1 of 2)


/ (ˈmaɪkrəʊ) /

  1. very small

British Dictionary definitions for micro- (2 of 2)


combining form
  1. small or minute: microspore

  2. involving the use of a microscope: micrography

  1. indicating a method or instrument for dealing with small quantities: micrometer

  2. (in pathology) indicating abnormal smallness or underdevelopment: microcephaly; microcyte Compare macro- (def. 2)

  3. denoting 10 –6: microsecond Symbol: μ

Origin of 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

Scientific definitions for micro-


  1. 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.