millimetre

• millimeter (US)
• millimètre (rare)

From French millimètre, equivalent to milli- +‎ metre.

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millimetre (plural millimetres)

2. An SI/MKS unit of measure, the length of ¹⁄₁₀₀₀ of a metre. Symbol: mm

   Synonyms: mm, ㎜; mil (informal), mill (informal)

   Holonyms: centimetre < decimetre < metre < kilometre < megametre < gigametre < terametre < petametre

   Meronyms: picometre < nanometre < micrometre

   • 2025 August, “The International System of Units (SI)”, in Bureau International des Poids et Mesures‎^[1], archived from the original on 17 September 2025, page 147:

     It is not permissible to use abbreviations for unit symbols or unit names, such as sec (for either s or second), sq. mm (for either mm² or square millimetre), cc (for either cm³ or cubic centimetre), or mps (for either m/s or metre per second).

• millimetric

• millimeter