millimeter
Americannoun
-
millimeters
plural
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of millimeter
First recorded in 1800–10; from French millimètre; see milli-, meter 1
Explanation
A millimeter is a tiny unit of measurement. The thickness of a dime is a little more than a millimeter, and there are a thousand millimeters in a meter. If you're using metric units to measure the length of something, you'll be dealing in meters and variations on meters, including millimeters. Look at a ruler that includes centimeters, the units of metric measurement that are closest in length to inches. The smallest units marked on the ruler are millimeters — there are ten of them in each centimeter. Although the word millimeter sounds like "million," it actually means "thousandth of a meter."
Vocabulary lists containing millimeter
Measurement and Data
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Florida's B.E.S.T. Roots: meter, metr
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
The researchers eventually made progress using electron cryotomography, a high-resolution 3D imaging method capable of revealing structures at the scale of a millionth of a millimeter.
From Science Daily ● Sep. 3, 2026
They grow about a centimeter or two a year and by sampling cores at the millimeter scale, the team was able to develop windows of monthly temperature records scattered across the past millennium.
From Barron's ● Aug. 27, 2026
One method for producing millimeter waves relies on a device known as a microcomb.
From Science Daily ● Aug. 24, 2026
"That has paid off really well for us because there are a lot of people out there that are seeking that 70 millimeter presentation."
From Barron's ● Jul. 26, 2026
For the first time I feel the weight of every single inch, every millimeter, of the six feet between us.
From "Five Feet Apart" by Rachael Lippincott
When the median caudal filament and two cerci were included, the total length reached 49.66 millimeters.
From Science Daily ● Aug. 27, 2026
Although the physical ring may measure only a few millimeters, the total effective distance traveled by the light depends on how little energy is lost from the waveguide each time it goes around.
From Science Daily ● Aug. 17, 2026
Sea-level rise is measured in millimeters, so tiny drifts in the reference frame prevent accurate calculations of coastal risk.
From The Wall Street Journal ● Aug. 7, 2026
The region, made up of mountains surrounded by a desert steppe, receives just over 100 millimeters of annual rainfall, classifying it as an desert.
From Barron's ● Jun. 15, 2026
A marvel of miniature engineering, the T-50 had a lens only four millimeters wide.
From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
