from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A device for measuring very small distances, objects, or angles, especially one based on the rotation of a finely threaded screw, as in relation to a microscope.
  • n. A unit of length equal to one thousandth (10-3) of a millimeter or one millionth (10-6)of a meter.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. An SI/MKS unit of measure, the length of one one-millionth of a meter. Symbols: µm, um, rm
  • n. A device used to measure distance very precisely but within a limited range, especially depth, thickness, and diameter.

from the GNU version of the Collaborative International Dictionary of English

  • n. An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass.

from The Century Dictionary and Cyclopedia

  • n. An instrument for measuring microscopic lengths and angles.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a metric unit of length equal to one millionth of a meter
  • n. caliper for measuring small distances


from Wiktionary, Creative Commons Attribution/Share-Alike License

micro- +‎ meter

from Wiktionary, Creative Commons Attribution/Share-Alike License

From French micrometre


  • In 2001 Japanese scientists made a tiny sculpture of a bull that measured 10 micrometers by seven (a micrometer is one-thousandth of a millimeter).

    June 2007

  • The word micrometer now seems to be used only to refer to the instrument for measurement, the former usage MIcrometer now being supplanted by the word micron.

    VERBATIM: The Language Quarterly Vol IV No 3

  • This is done by submitting exactly similar cylinders of lead to a crushing under weights acting without initial velocity, and measuring the reduced heights of the cylinders; from these results a table is constructed establishing empirical relations between the reduced heights and the corresponding weights; the cylinders are measured both before and after insertion in the pressure gauge by means of an instrument known as the micrometer calipers (Fig. 57). [

    Nitro-Explosives: A Practical Treatise

  • They are trying to measure with a micrometer, mark with a dull pencil, and cut with a chain saw.

    Coyote Blog » Blog Archive » Example of Climate Work That Needs to be Checked and Replicated

  • While you don't necessarily need a micrometer to calibrate a leader to your line, you ought to consider holding loops of the same size of the butt section of the leader you intend to use and the end section of your fly line next to each other for comparison.

    How to Choose Leaders and Tippets when Fly Fishing

  • Imagine it: a flower blossoming inside the brain, nanometer stalks splitting away from a micrometer stem.

    World Wide Mind

  • A cross-section of a capillary, showing how much room a nanowire the gray-shaded circle would take up within it. “1 µm” means “1 micrometer,” or one millionth of a meter.

    World Wide Mind

  • We can't put them in a test tube or measure them with a micrometer or scale.

    Behe and Gene discuss the Evolution of the Flagellum

  • And here, as I promised to be faithful, I may add that for the glass micrometer and the little black magnifying glass, they charged me an additional 4/6. —

    Letter 134

  • The micrometer you will see is scratch'd into squares so minute that each square form'd by the intersections is but the ten thousandth part of an inch.

    Letter 134


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  • Also a device used to measure parts.

    September 23, 2008