mm

IPA/ˌɛmˈɛm/
KK[m]IPA/m/

mm — abbreviation

1. the short form used in measurements, labels, and notes for millimetre

1.abbreviationA2
Definition

the short form used in measurements, labels, and notes for millimetre

Example

Mira bought a 6 mm drill bit for the shelf brackets.

number + mm before a tool noun

The rain gauge showed 18 mm after the storm ended.

number + mm for recorded rainfall

Common collocations
  • 6 mm drill bit
  • 18 mm rainfall
  • 12 mm hem
  • 35 mm camera
  • 3 mm gap
Synonyms
  • millimetre

    the full British spelling used when the unit is written out

  • millimeter

    the full American spelling used when the unit is written out

Grammar Patterns

number + mm

mm + noun

Usage Note

It usually comes after a number in measurements and product descriptions. The abbreviation is the same in British and American English even though the full word is spelled 'millimetre' in British English and 'millimeter' in American English.

Common Mistakes

The box is 30 millimetre wide.
The box is 30 mm wide.
Use 'mm' as the written short form when a measurement follows a number.
I need a ten mm drill bit.
I need a 10 mm drill bit.
Measurement abbreviations are normally written with numerals, not spelled-out numbers.

mm — noun

Word family

Synonym discussion

Sense: abbreviation/1

mm is the short written form for millimetre, so it is the choice you see after numbers on labels, plans, and product information. Millimetre and millimeter are the full words, with the British spelling using -re and the American spelling using -er. Writers choose the full form when they want a complete sentence or a more formal explanation, but they switch to mm in measurements. cm is also a metric unit, but it is ten times larger, so it is not interchangeable with mm. If a screw is 6 mm wide, writing 6 cm would describe a much bigger object.

mm ↗millimetre ↗millimeter ↗cm ↗

Common collocations

Nouns

Phrases

  • number + mm
  • number + mM

Prepositions

  • at
  • from ... to

Etymology

LatinFrenchEnglish

This abbreviation comes from scientific and technical writing. In the common measurement sense, mm is built from milli-, meaning 'one thousandth', and metre. In chemistry, the closely related form mM is used for millimolar, combining the same milli- element with molar.