milli-

IPA/mɪl.ɪ-/
IPA/mɪl.ɪ-/

milli- — prefix

1. used before a unit name to show a value equal to 0.001 of the base unit

1.prefixB2
Definition

used before a unit name to show a value equal to 0.001 of the base unit

Example

In science class, milli- turns meters into the smaller unit millimeters.

milli- + unit noun for one thousandth of the base unit

The recipe scale uses milli- when liquid amounts are too small for liters.

Common collocations
  • millimeter
  • milligram
  • milliliter
  • millisecond
  • milliamp
Synonyms
  • micro-

    marks an even smaller amount, one millionth of the base unit.

  • centi-

    marks one hundredth, so it is larger than milli-.

Antonyms
  • kilo-

    marks one thousand times the base unit instead of a small fraction.

Grammar Patterns

milli- + unit noun

Usage Note

Usually attached to names of metric units in science, medicine, and technology. It tells the reader that the quantity is much smaller than the basic unit.

Common Mistakes

The tube holds five liters, not five milliliters.
The tube holds five milliliters, not five liters.
milli- marks a much smaller unit, so switching it changes the size by a large amount.

milli- — combining form

Word family

Synonym discussion

Sense: prefix/1

These metric forms all change the size of a unit, but each points to a different scale. 'Centi-' means one hundredth, so it is larger than 'milli-'. 'Micro-' means one millionth, making it much smaller than 'milli-'. 'Kilo-' moves in the opposite direction and marks a quantity one thousand times larger than the base unit. 'Nano-' goes even smaller than 'micro-'. If a medicine label says milligram, the amount is small but still larger than a microgram. If a road sign says kilometer, the unit is much larger than a meter.

centi-micro-kilo-nano- ↗

Common collocations

Nouns

Phrases

  • milli- + gram
  • milli- + liter
  • milli- + meter
  • milli- + second

Etymology

LatinFrenchScientific English

Milli- comes from Latin mille, meaning 'thousand'. Modern scientific English adopted it through the metric system to mark values that are one thousandth of a standard unit, which is why it appears in words such as millimeter, milligram, and millisecond.