Meaning & use
millimeter
Last updated
Meaning
nouncountabletechnical
A unit of length equal to one thousandth of a meter.
Grammar: Countable; plural millimeters. Abbreviated mm. British English spells it millimetre.
Patterns
- a millimeter of something
- measured in millimeters
- X millimeters long/wide/thick
The wire is only two millimeters thick.
Please measure the gap in millimeters, not centimeters.
A millimeter of rain fell overnight, which is almost nothing.
Word forms
| plural | millimeters |
|---|
Common combinations
- a few millimeters
- The crack is only a few millimeters wide.
- millimeters of mercury
- Blood pressure is often reported in millimeters of mercury.
- to the nearest millimeter
- Measure the length to the nearest millimeter.
- square millimeters
- The area is about 25 square millimeters.
Synonyms and how they differ
- mm
- The abbreviation; use it in writing after a number, as in 10 mm.
Word family
- millimetric adjective
- Relating to measurements in millimeters, as in millimetric precision.
Commonly confused: millimeter or milliliter? millimeter or micrometer?
millimeter vs milliliter
A milliliter measures volume (one thousandth of a liter), while a millimeter measures length.
millimeter vs micrometer
A micrometer is one thousandth of a millimeter, so it is much smaller.
Practice
How many millimeters are there in 3.5 centimeters?
Choose one answer.
One centimeter equals 10 millimeters, so 3.5 cm × 10 = 35 mm. Multiplying by 100 would give 350 mm, which is the conversion for meters to centimeters, not centimeters to millimeters.
Make it your own
Write a sentence using “millimeter”, then check it and compare it with the examples above.