milli-

Milli- is a combining form used like a prefix meaning “thousand.” In names of units of measure, particularly in the metric system, milli- means “one thousandth.” It is often used in scientific and technical terms.

Milli– comes from the Latin mille, meaning “thousand.” The Greek translation of mille is chī́lioi, “a thousand,” which is the source of English terms such as kilogram and kilometer. To learn more, check out our entries for both words.

An example of a word you may have encountered that features milli– is millisecond, “one thousandth of a second.”

The milli– part of millisecond literally means “thousand.” But, because –second is a unit of measure (of time), here milli– means “one thousandth.” Millimeter literally means “one thousandth of a second.”

What are some words that use the combining form milli-?

• milliampere
• millibar
• millicurie
• millimeter (using the equivalent form of milli- in French)
• millipede (using the equivalent form of milli- in Latin)

What are some other forms that milli– may be commonly confused with?

• melano-
• melo-

Not every word that begins with the exact letters milli-, such as milliner, is necessarily using the combining form milli– to denote “thousand.” Learn why milliner means “hat-maker” at our entry for the word.

The combining form –pede means “having a foot.” With this in mind, what does millipede literally mean?