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 strands are often less than a millimeter around and can be 3-plus feet in length, observatory officials said. —Sara Schilling, Sacramento Bee, 28 Jan. 2025

Perez Intended as both a showcase for client meetings and a home base for Thornton and her team of 15, the space couldn’t fall a millimeter short of her exacting standards. —David Foxley, Architectural Digest, 23 Jan. 2025

Check the product listing—there's usually a case thickness limit in millimeters. —Julian Chokkattu, WIRED, 19 Jan. 2025

Hair grows at a rate of about a third of a millimeter a day, or about 15 centimeters a year, which is nearly 6 inches.4 2. —Nancy Lebrun, Verywell Health, 13 Jan. 2025

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