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

Compact, millimeter-scale detectors could complement large observatories and help probe low-frequency waves that are currently hard to detect. —Rupendra Brahambhatt, Interesting Engineering, 21 Mar. 2026

Melanosomes are tiny structures, roughly one-thousandth of a millimeter long, responsible for producing pigment. —Ryan Brennan, Charlotte Observer, 20 Mar. 2026

Melanosomes are tiny structures, roughly 1/1000th of a millimeter long. —Ryan Brennan, Miami Herald, 20 Mar. 2026

This laser goes significantly deeper, penetrating up to 10 millimeters into the dermis, Eunice Louis-Jacques, registered nurse and aesthetic lead at SEV Laser, told the AJC. —Avery Newmark, AJC.com, 18 Mar. 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