millimeter
Americannoun
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:
As part of the restructure, ownership of a facility making 200 millimeter chips, in which Tower currently holds a majority stake, will transfer to Nuvoton Technology.
From The Wall Street Journal ● Jul. 14, 2026
The group announced a restructuring of its Japan operations in March, which will result in Tower taking full ownership of its Japan-based factory making 300 millimeter chips.
From The Wall Street Journal ● Jul. 14, 2026
The chip is giant, taking up an entire 300 millimeter silicon wafer, almost a foot long across the chip’s diagonal line.
From Barron's ● May 11, 2026
For scale, a nanometer is one millionth of a millimeter.
From Science Daily ● Mar. 4, 2026
The fireworks sprinkled down, dissolving in the air just before they reached the ground, and the children were pulled, one millimeter and one second at a time, into Manhattan and adulthood.
From "Extremely Loud and Incredibly Close" by Jonathan Safran Foer
Clarke’s team has spent the last two years sweating grams, watts, millimeters and pennies from every component, system or process, over and over.
From The Wall Street Journal ● Jun. 20, 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
The new PCs will be as slim as 14 millimeters thick, and the lightest will weigh less than 3 pounds.
From The Wall Street Journal ● Jun. 1, 2026
Giant atoms have defined energy levels and follow the rules of quantum mechanics, yet they can reach sizes of up to millimeters, making them visible to the naked eye.
From Science Daily ● Apr. 13, 2026
The film itself, loaded into the T-50 by specially trained technicians, was barely wider than the lens—a mere five millimeters.
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.
