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 microplastics problem Microplastics are tiny shards of plastic smaller than 5 millimeters. —Lex Harvey, CNN, 17 Dec. 2024

The system works best when detecting objects about 8 millimeters in diameter. —IEEE Spectrum, 11 Dec. 2024

Blue light penetrates one millimeter to reduce inflammation and bacteria, and helps your body clock. —Beth Landman, The Hollywood Reporter, 4 Dec. 2024

Blood pressure is measured by two numbers, expressed in millimeters of mercury (mm Hg): the systolic (upper or first) number and the diastolic (lower or second) number. —Corey Whelan, Verywell Health, 1 Dec. 2024

Word History

Etymology

French millimètre, from milli- + mètre meter

First Known Use

1797, in the meaning defined above

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