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 insider site suggests that the SE model could see case see an increase to 41 millimeters and 45 millimeters. —James Powel, USA Today, 5 Sep. 2025

Blood pressure is measured in millimeters of mercury, which is abbreviated as mm Hg. —Jen Christensen, CNN Money, 30 Aug. 2025

This allows manufacturers to join profiles with wall thicknesses over 20 millimeters. —Georgina Jedikovska, Interesting Engineering, 29 Aug. 2025

The attractive and sturdy case is one millimeter smaller than previous versions of the watch, which is barely worth mentioning. —Anthony Demarco, Forbes.com, 28 Aug. 2025

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