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

At its heart sits a nested set of tracking systems designed to reconstruct thousands of particle trajectories per collision with millimeter precision. —Tejasri Gururaj, Interesting Engineering, 29 Jan. 2026

Your snowboard and gear will also stay protected with 10 millimeters of dense, thick EPE foam throughout the entire bag. —Nathan Allen, Travel + Leisure, 29 Jan. 2026

He was armed with a 9-millimeter handgun that was in plain view on the driver's side floorboard. —Natalie Morales, CBS News, 27 Jan. 2026

Springtails range in length from less than a millimeter to about 10 millimeters — roughly three-eighths of an inch. —Miriam Fauzia, Dallas Morning News, 27 Jan. 2026

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