In the International System of Units and other metric systems of units, one-thousandth of the unit to which it is prefixed; that is, multiplying the unit to which it is attached by 10-3. Symbol: m
Milli- is added to some nouns that refer to units of measurement in order to form other nouns referring to units a thousand times smaller. a small current, around 5 milliamps. One thousandth (10-): millisecond. a 1000th part of a unit