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SI units

the units of measurement generally accepted for all scientific and technical uses; together they make up the International System of Units. (See also metric system.) The abbreviation SI, from the French Système International d'Unités, is used in all languages. There are seven base SI units, defined by specified physical measurements, and two supplementary units. Units are derived for any other physical quantities by multiplication and division of the base and supplementary units. The derived units with special names are shown in the accompanying table.

SI is a coherent system. This means that units are always combined without conversion factors. The derived unit of velocity is the meter per second (m/s); the derived unit of volume is the cubic meter (m3). If you know that pressure is force per unit area, then you know that the SI unit of pressure (the pascal) is the unit of force divided by the unit of area and is therefore equal to 1 newton per square meter.

The metric prefixes can be attached to any unit in order to make a unit of a more convenient size. The symbol for the prefix is attached to the symbol for the unit, e.g., nanometer (nm) = 10−9 m. The units of mass are specified in terms of the gram, e.g., microgram (μg) = 10−9 kg.

Only one prefix is used with a unit; the use of units such as the millimicrometer is no longer acceptable. When a unit is raised to a power, the power applies to the prefix as well, e.g., a cubic millimeter (mm3) = 10−9 m3. When a prefix is used with a ratio unit, it should be in the numerator rather than in the denominator, e.g., kilometers/second (km/s) rather than meters/millisecond (m/ms). Only prefixes denoting powers of 103 are normally used. Hecto-, deka-, deci-, and centi- are usually attached only to the metric system units gram, meter, and liter.

Owing to the force of tradition, one noncoherent unit, the liter, equal to 10−3 m3, or 1 dm3, is generally accepted for use with SI. The internationally accepted abbreviation for liter is the letter l; however, this can be confused with the numeral 1, especially in typescript. For this reason, the capital letter L is also used as a symbol for liter. The lower case letter is generally used with prefixes, e.g., dl, ml, fl. The symbols for all other SI units begin with a capital letter if the unit is named after a person and with a lower case letter otherwise. The name of a unit is never capitalized.

li·ter (L, l),

(lē'tĕr), Although the SI unit of volume is the cubic meter and, by extension, the cubic centimeter (1 cm3=0.000 001 m3), the liter and its submultiples are preferred to the cubic meter and its submultiples for the expression of volumes and substance or mass concentrations in clinical chemistry. For practical purposes 1 cubic decimeter (dm3) = 1 liter (L). It recommended that capital (L) be used as the abbreviation of liter because the lowercase l can easily be misread as the numeral 1.
A measure of capacity of 1000 cubic centimeters or 1 cubic decimeter; equivalent to 1.056688 quarts (U.S., liquid).
[Fr., fr. G. litra, a pound]


/li·ter/ (L) (lēt´er) a basic unit of volume used for liquids with the SI system, equal to 1000 cubic centimeters, or 1 cubic decimeter, or to 1.0567 quarts liquid measure.

liter (L)

Etymology: Fr
a derived unit of volume equivalent to 1.057 quarts and defined as the volume occupied by a mass of 1 kg of water at standard temperature and pressure.


(L) (lē'těr)
A measure of capacity of 1000 cubic centimeters or 1 cubic decimeter; equivalent to 1.056688 quarts (U.S., liquid).
Synonym(s): litre.
[Fr., fr. G. litra, a pound]

liter (lēˑ·ter),

n a metric unit of measure defined as one cubic decimeter or the amount of volume occupied by one kilogram of pure water. It is written as L or dm3.


(L) (lē'těr)
A measure of capacity of 1000 cubic centimeters or 1 cubic decimeter; equivalent to 1.056688 quarts (U.S., liquid).
Synonym(s): litre.
[Fr., fr. G. litra, a pound]


the unit of capacity of the metric system, being equal to 1 cubic decimeter; equivalent to 1.1365 Imperial quarts (1.0567 American quarts) liquid measure. See si units. Abbreviated l (or sometimes L).

Patient discussion about liter

Q. I need a Lyme LIterate Doctor in MA Moving to MA - son has chronic Lyme

A. Hi! Where are you moving to? I'm here in Boston with early Lyme that I hope is not going chronic (the treatment I've taken so far is only suppressing it, and it comes back if I stop antibiotics).

Apparently there is a Dr. Sam Donta who works in Falmouth and Boston: 508-539-6666. But he is pretty busy.

More discussions about liter
References in periodicals archive ?
The new information could undercut that argument, and bolster claims of environmentalists who want the limit set at 100 milligrams per liter and oppose the basin plan being changed.
City officials are still planning to go to the water board meeting to ask members to work with the sanitation district and come to an agreement about the cost of the proposal to set the standard at 100 milligrams per liter, Rietzel said.
The proposal to reduce the maximum chloride level to 143 milligrams per liter is the result of that study.
Darcy is scheduled to speak at the water board hearing on July 27 in Pasadena to voice the city's support for the 143 milligrams per liter standard.
Diesel on credit card: minimum 1000 liter maximum 900 000 liters;
Motor gasoline: 4,000 thousand liters minimum, maximum 5,800 thousand liters;
The system can mold containers up to 60 liters, a spokesman said.
Quantity: Lot number 1 (by coupons or bulk ): - petrol A -95 - 9000 liters - petrol A -92 - 52 211 liters - diesel GP - 22 500,5 liters.
Summary: TEHRAN (FNA)- Average daily gasoline consumption stood at less than 60 million liters per day in the first week of December.
1 million liters during the week ending on January 06 that is a record low since the beginning of autumn.
20 per 1000 liters and gasoil selling for BGN 2251.
Summary: BEIRUT: The prices of 20 liters of gasoline increased by LL100 and 20 liters of kerosene jumped by LL400.