mil·​li·​me·​ter | \ ˈmi-lə-ˌmē-tər How to pronounce millimeter (audio) \
variants: US millimeter or British millimetre

Definition of millimeter

: a unit of length equal to ¹/₁₀₀₀ meter — see Metric System Table

Examples of millimeter in a Sentence

Recent Examples on the Web This basic type of navigation works best for short distances, generally less than half a millimeter. Lucy Hicks, Science | AAAS, "Watch amoebas solve a microscopic version of London’s Hampton Court Maze," 27 Aug. 2020 Tesla wants to use millimeter-wave radar technology as a means to detect children and other occupants left in its vehicles. Roberto Baldwin, Car and Driver, "Tesla Looks to Airport-Style Scanning So Kids Aren't Left in Cars," 21 Aug. 2020 The object was propelled by an alien machine, such as a lightsail—a wide, millimeter-thin machine that accelerates as it's pushed by solar radiation. Rafi Letzter, Scientific American, "Mystery of Interstellar Visitor 'Oumuamua Gets Trickier," 19 Aug. 2020 That's because Verizon primarily uses the fastest part of the 5G spectrum, called high-band millimeter wave, which is spotty and only works in certain blocks, vs. entire neighborhoods. Jefferson Graham, USA TODAY, "5G networks are not shining. But with new phones from Samsung and Apple, could this be 5G's year?," 17 Aug. 2020 Since tardigrades are mostly colorless, deCarvalho used fluorescent dye molecules to stain the tardigrade’s internal structures, revealing an eye-popping look inside a creature that typically grows no longer than one millimeter in length. Nora Mcgreevy, Smithsonian Magazine, "Colorful Image Lights Up Microscopic Guts of ‘Water Bear’," 13 Apr. 2020 The vast majority of clear tote bags are made from PVC or plastic that is half a millimeter thick. Sian Babish,, "The best clear tote bag," 15 Aug. 2020 Ice melting in Greenland contributes more than a millimeter rise to sea level every year, and that's likely to get worse. Max Claypool And Brandon Miller, CNN, "Greenland's ice sheet has melted to a point of no return, according to new study," 14 Aug. 2020 Fleegle says velvet has 12 hair filaments per square millimeter, each one measuring 5 mm long. Josh Honeycutt, Outdoor Life, "How Much More Antler Will Your Target Buck Grow Before Opening Day?," 10 Aug. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'millimeter.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of millimeter

1797, in the meaning defined above

History and Etymology for millimeter

French millimètre, from milli- + mètre meter

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Time Traveler for millimeter

Time Traveler

The first known use of millimeter was in 1797

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Statistics for millimeter

Last Updated

11 Sep 2020

Cite this Entry

“Millimeter.” Dictionary, Merriam-Webster, Accessed 19 Sep. 2020.

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More Definitions for millimeter


How to pronounce millimeter (audio)

English Language Learners Definition of millimeter

: a length equal to 1/1000 meter


mil·​li·​me·​ter | \ ˈmi-lə-ˌmē-tər How to pronounce millimeter (audio) \

Kids Definition of millimeter

: a unit of length equal to 1/1000 meter


variants: or chiefly British millimetre \ ˈmil-​ə-​ˌmēt-​ər How to pronounce millimetre (audio) \

Medical Definition of millimeter

: one thousandth of a meter abbreviation mm

More from Merriam-Webster on millimeter

Nglish: Translation of millimeter for Spanish Speakers

Britannica English: Translation of millimeter for Arabic Speakers

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