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

Because the Depression would hold a lot of water — 290 mi3 (1,200 km3), or about 30% the volume of the Grand Canyon — filling it would reduce worldwide ocean levels by 3 millimeters, and its constant evaporation would slow the rise of ocean levels by up to 6%. —Big Think, 17 Oct. 2025

Researchers at the University of California San Diego have developed a soft robotic skin that allows vine-like robots just a few millimeters wide to navigate tight and fragile environments. —Neetika Walter, Interesting Engineering, 16 Oct. 2025

Macroplastics are defined as plastic items with a dimension greater than or equal to 5 millimeters. —Alexandra Harrell, Sourcing Journal, 16 Oct. 2025

Police seized a 9 millimeter Glock 19 pistol from the defendant with eight live rounds remaining in the 10-round magazine. —Rick Sobey, Boston Herald, 14 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