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

After 50 millimeters of rainfall in New South Wales, Australia — where each year, for three weeks, a group of British celebrities live and carry out grim challenges in a bid to win food — the talent were moved away and filming was delayed for three hours. —Lily Ford, HollywoodReporter, 26 Nov. 2025

Its 66-millimeter waist delivers exceptional edge grip, hard-snow integrity, and stability, earning it top marks in carving at our annual SKI Test. —Jenny Wiegand, Outside, 19 Nov. 2025

Each wicket sits on a 200-millimeter-deep metal tray, with another 50mm above. —Michael Bailey, New York Times, 19 Nov. 2025

Today’s state-of-the-art optical clocks offer accuracy to 18 decimal places, which is roughly equivalent to measuring the distance from Earth to the Moon to one-millionth of a millimeter. —Neetika Walter, Interesting Engineering, 17 Nov. 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