millimeter

noun

mil·​li·​me·​ter ˈmi-lə-ˌmē-tər 

variants US millimeter or British millimetre

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

Examples of millimeter in a Sentence

Recent Examples on the Web

The Arabian and Eurasian plates continue to move toward each other at around 20 millimeters a year, sometimes triggering deadly earthquakes. —Stephanie Pappas, Scientific American, 6 Mar. 2026

Equipment is customized to the millimeter. —Oksana Masters, Time, 6 Mar. 2026

Large cities surrounded by water -- like Boston, New Orleans and San Francisco -- will be among the regions that could experience flooding in the near future due to land elevation changes combined with sea level rise -- about 4 millimeters per year, the 2024 study found. —Julia Jacobo, ABC News, 4 Mar. 2026

This low-power millimeter-wave radar sensor gives self-driving cars a clearer, more accurate view of traffic by feeding them essential data from the surrounding road. —Mrigakshi Dixit, Interesting Engineering, 3 Mar. 2026

Word History

Etymology

French millimètre, from milli- + mètre meter

First Known Use

1797, in the meaning defined above

Rhymes for millimeter

• amphitheater
• centimeter
• centimetre
• decimeter
• ergometer
• expositor
• gasometer
• gravimeter
• hexameter
• manometer
• milliliter
• millimetre

Kids Definition

millimeter

noun

mil·​li·​me·​ter ˈmil-ə-ˌmēt-ər 

: a measure of length equal to ¹⁄₁₀₀₀ meter see metric system table

Medical Definition

millimeter

noun

mil·​li·​me·​ter

variants or chiefly British millimetre

ˈmil-ə-ˌmēt-ər 

: one thousandth of a meter

—abbreviation mm