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 reality of leading a dozen or so enthusiasts of varying levels makes route selection and choosing the degree of challenge a game of millimeters. —Basem Wasef, Robb Report, 18 Mar. 2025

The Santa Barbara groundwater basin, which has been continuously replenishing since 2018, has rising areas of several millimeters per year, according to the researchers' mapping. —Janet Loehrke, USA TODAY, 13 Mar. 2025

Microplastics are plastic particles smaller than five millimeters. —Bill Frist, Forbes, 13 Mar. 2025

Though inconspicuous—the largest reach only about one millimeter in length—tardigrades are incredibly resilient. —Paulina Rowińska, Smithsonian Magazine, 12 Mar. 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