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 It is sometimes called microproppant because of its small size: 400-500 mesh (about 0.05 mm or 1/20 of a millimeter). Ian Palmer, Forbes, 19 May 2021 The trunk of a Huon pine grows at a rate of about a millimeter a year. Steve King, Condé Nast Traveler, 19 Aug. 2021 With a side-zipper entry, putting these on is effortless, and the high-top design paired with three-millimeter-thick neoprene (not to mention five-millimeter neoprene insoles) keeps ankles and feet toasty and comfortable pretty much year-round. Ebony Roberts, Outside Online, 11 June 2021 On May 12, a routine inspection of a robotic arm on the International Space Station revealed a five-millimeter-wide hole in its thermal covering. Theresa Machemer, Smithsonian Magazine, 2 June 2021 And Karl told me, no, no, not on the mouth, just half a millimeter before touching lips. Nicole Phelps, Vogue, 5 July 2021 All in all, the chips have a total volume of less than 1 cubic millimeter. Courtney Linder, Popular Mechanics, 11 June 2021 The authors say that resolution of the tongue is about half a millimeter, while that of fingertips is twice as large at one millimeter. Claire Bugos, Smithsonian Magazine, 28 May 2021 Clinical latency, or asymptomatic HIV infection, in which HIV reproduces at lower levels. AIDS, in which the amount of CD4 cells fall below 200 cells per cubic millimeter of blood (as opposed to the normal level of 500-1,500). Cnn Editorial Research, CNN, 6 June 2021

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

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The first known use of millimeter was in 1797

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Last Updated

24 Sep 2021

Cite this Entry

“Millimeter.” Dictionary, Merriam-Webster, Accessed 25 Sep. 2021.

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More Definitions for millimeter



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 millimeter (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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