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 pipes were miniature, with a diameter of only 18 millimeters and a wall thickness of just 3 millimeters. —Aman Tripathi, Interesting Engineering, 30 Oct. 2025

The device uses a tiny 2 millimeter by 2 millimeter photovoltaic implant that is only 30 micrometers thick, and thinner than a strand of hair. —Kurt Knutsson, FOXNews.com, 28 Oct. 2025

The boy, whose identity was not disclosed, ate between 80 and 100 neodymium magnets, each five millimeters by two millimeters in size, according to the report. —Hanna Park, CNN Money, 27 Oct. 2025

This is maybe a few square millimeters of it. —Nick Canepa, San Diego Union-Tribune, 25 Oct. 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