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

Surrounding the headliners are grumpy arena security, who spend the night wearing baffled expressions watching a sea of adults cheer and laugh and applaud over imaginary characters engaged in battles no one can actually see, and rolls of acrylic dice just 16 millimeters in size. —Eric Francisco, Rolling Stone, 1 Mar. 2025

Microplastics are classified as being smaller than 5 millimeters in size. —Dan Perry, Newsweek, 28 Feb. 2025

That glass was then ground into particles ranging from 0.85 to 2 millimeters in width (for reference, grains of sand range from around 0.1 to 2 mm). —Ben Coxworth, New Atlas, 24 Feb. 2025

The point shifted its position by just 3 millimeters on the plates, which factored out to a world approximately 43 times farther from the sun than the Earth is. —Jeffrey Kluger, TIME, 18 Feb. 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