• synonyms


  1. any of various devices for measuring minute distances, angles, etc., as in connection with a telescope or microscope.
  2. Also called mike. micrometer caliper. a precision instrument with a spindle moved by a finely threaded screw, for the measurement of thicknesses and short lengths, commonly used by machinists for turning shafts or boring holes.
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Also especially British, mi·crom·e·tre.

Origin of micrometer1

First recorded in 1660–70; micro- + -meter


  1. micron(def 1).
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Origin of micrometer2

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for micrometer

Historical Examples

  • Gascoigne overcame this difficulty by his invention of the micrometer.

    The Astronomy of Milton's 'Paradise Lost'

    Thomas Orchard

  • Its use is to act as a micrometer or measurer of small distances.

  • The micrometer and barrel may be procured from any of the manufacturers of measuring instruments.

  • For this half inch it is threaded on the inside and acts as a micrometer nut.

  • The micrometer may be used in combination with a 4-, 6-, 9-, or 12-inch scale.

British Dictionary definitions for micrometer


  1. any of various instruments or devices for the accurate measurement of distances or angles
  2. Also called: micrometer gauge, micrometer calliper a type of gauge for the accurate measurement of small distances, thicknesses, diameters, etc. The gap between its measuring faces is adjusted by a fine screw, the rotation of the screw giving a sensitive measure of the distance moved by the face
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Derived Formsmicrometry, nounmicrometric (ˌmaɪkrəʊˈmɛtrɪk) or micrometrical, adjective
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

Word Origin and History for micrometer


1660s, from micro- + -meter. Originally a telescope attachment; from 1884 as a craftsman's fine measuring tool. Related: Micrometry; micrometric.

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Online Etymology Dictionary, © 2010 Douglas Harper

micrometer in Science


  1. A device for measuring very small distances, angles, or objects, especially one based on the rotation of a finely threaded screw, as in relation to a microscope.
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  1. A unit of length in the metric system equal to one millionth (10-6) of a meter. Also called micron
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.