base unitOne of the seven units that the others are built on. All other metric units are combinations of the seven. The kilogram is a base unit; the gram is not.
centi-The prefix that divides a unit by a hundred. Its symbol is c. A centigram is a hundredth of a gram.
convertTo rewrite a measurement in a different unit. Changing the unit does not change the amount: 2.5 kilometers and 2,500 meters are the same distance.
decimalGoing up and down in steps of ten. Metric units go up in tens: 10 centimeters make a decimeter, and 10 decimeters make a meter.
gramThe mass of a single dollar bill, more or less. Its symbol is g. A nickel is about 5 grams and a penny about 2.5.
kilo-The prefix that multiplies a unit by 1,000. Its symbol is a small k. Kilo- was one of the eight prefixes adopted in 1795.
literThe usual metric unit for a volume of liquid. Picture a cube with edges of 10 centimeters: that is one liter. Its symbol is a capital L, so that it is not mistaken for the number one.
Show all 36 terms (29 more)
Metric units and prefixes, continued
meterThe unit on which all metric lengths are built. Its symbol is m. A volleyball net is 1 meter wide, and a football field is about 90 meters long.
metric systemThe decimal system of units used around the world. Its modern form is the International System of Units. Seventeen countries, the United States among them, signed the Treaty of the Meter in Paris on May 20, 1875.
milli-The prefix that divides a unit by a thousand. Its symbol is m. A dime is about 1 millimeter thick.
power of tenA number like 1,000, made by multiplying tens. Ten to the power of three is 1,000, the number that kilo- stands for.
prefixA short add-on fixed before a unit name to scale it. There are 24 metric prefixes. The largest, quetta-, stands for a 1 followed by 30 zeros.
Everyday units and decimals 12
centimeterOne of the hundred equal steps on a meter stick. Its symbol is cm. A pencil is about 19 centimeters long.
decimal pointThe dot written between the ones and the tenths. In 2.5 meters the point comes after the 2. A number smaller than one is written with a zero in front, as in 0.5.
degree CelsiusThe metric unit of temperature for everyday use. Zero is the freezing point of water and about 100 its boiling point. A comfortable room is about 20 degrees Celsius.
deka-The prefix that means ten. Its symbol is da, the only prefix symbol with two letters. Deca- is the British spelling.
hundredthOne share when a whole is split 100 ways. It is written 0.01, in the second place after the point. A dollar has 100 cents, so a cent is a hundredth of a dollar.
kilogramThe only base unit named with a prefix. It is the unit of mass and equals 1,000 grams. A cat is about 5 kilograms and a bicycle about 15.
kilometerThe metric unit for distances between towns. It is 1,000 meters, and its symbol is km. The Mariana Trench is about 11 kilometers deep.
milliliterThe space inside a cube 1 centimeter on each side. Its symbol is mL. A thousand make a liter, and a soda can holds 355.
multiplyTo take a number a given count of times. To change a larger metric unit into a smaller one, multiply: 3 meters times 100 is 300 centimeters.
place valueHow much a digit counts for in the spot it holds. The metric prefixes line up with place values: kilo- with the thousands, centi- with the hundredths.
tenthOne share when a whole is split ten ways. It is written 0.1, in the first place after the point. The prefix for a tenth is deci-, as in decimeter.
thousandthOne share when a whole is split 1,000 ways. It is written 0.001, in the third place after the point. A milligram is a thousandth of a gram.
SI and derived units 12
derived unitA unit made by combining base units. The meter per second and the square meter are derived units. Twenty-two have special names.
exponentThe count of tens multiplied, written small and high. In 10 to the 3rd power the exponent is 3. A negative exponent gives a fraction: 10 to the minus 3 is one thousandth.
hertzThe unit for how often a wave repeats. It is the unit of frequency: one cycle every second. Its symbol is Hz, and a terahertz is a trillion hertz.
jouleThe amount of work in a 1-newton push over 1 meter. It is the unit of energy, and its symbol is J.
newtonThe unit in which pushes and pulls are measured. It is the unit of force, and its symbol is N. One newton speeds up 1 kilogram by 1 meter per second every second.
order of magnitudeA step of ten times in size. A kilometer is three orders of magnitude longer than a meter.
pascalThe unit for force spread over an area. It is the unit of pressure, and its symbol is Pa: one newton on one square meter.
quantityA property that can be measured, such as mass. A value is a number times a unit: the Washington Monument is 169 meters tall.
scientific notationA way to write numbers with powers of ten. The speed of light, 299,792,458 meters per second, is about 3 times 10 to the 8th.
SIThe metric system's official name, in two letters. It is short for the French Système International d'Unités. The treaty behind it now has 64 member states.
symbolThe letter or letters that stand for a unit. Symbols are the same in every language: m for meter, kg for kilogram, L for liter.
wattThe unit that tells how quickly a device uses energy. It measures power: a watt is a joule used each second. Its symbol is W, and a kilowatt is 1,000 watts.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: International System of Units, Metre, Litre, Gram, Kilogram, Kilometre, Celsius, Kilo-, Centi-, Milli-, Deca-, Metric prefix, SI base unit, SI derived unit, Physical quantity, Conversion of units, Decimal, Decimal separator, Positional notation, Power of 10, Order of magnitude, Scientific notation, Exponentiation, Newton (unit), Joule, Watt, Hertz and Pascal (unit). Convert, prefix, decimal, quantity, base unit, derived unit, order of magnitude, tenth, hundredth, thousandth, multiply, exponent and deka- rest on their entries in Wiktionary, the free dictionary (https://en.wiktionary.org/). The base units, the derived units, the prefixes and their history, the symbols, the treaty of 1875, the SI of 1960, the units of length, mass, volume and temperature and every everyday size (the dollar bill, the nickel, the penny, the dime, the pencil, the volleyball net, the football field, the soda can, the cat, the bicycle, the Mariana Trench, the Washington Monument, the comfortable room) were checked against nine pages of the Metric Program of the National Institute of Standards and Technology (https://www.nist.gov/pml/owm/metric-si): SI Units, Metric (SI) Prefixes, SI Units - Length, SI Units - Mass, SI Units - Volume, SI Units - Temperature, Understanding Metric, Unit Conversion and Everyday Estimation. The worked figures (2.5 kilometers, 300 centimeters, 3 times 10 to the 8th) are our own working. The fact after each meaning is from the same pages. Licence: own work
How it works
This metric system vocabulary worksheet prints meter, liter, gram, kilo-, centi-, milli-, prefix, convert and base unit, among twelve terms, to match to their meanings. The answer key is the last page.
Read the full guide
Everyday units and decimals
Set opens on Metric units and prefixes. The second set has kilometer, centimeter, kilogram, milliliter, degree Celsius, decimal point, place value, tenth, hundredth, thousandth, multiply and deka-.
SI and derived units
The third set has SI, derived unit, quantity, symbol, newton, joule, watt, hertz, pascal, order of magnitude, scientific notation and exponent.
Hecto-, deci-, mega- and micro- are words on the measurement word search, and length, mass and volume stand in the meanings, not among the terms.
Questions and answers
What are the 7 base units of the metric system?
The meter for length, the kilogram for mass, the second for time, the ampere for electric current, the kelvin for temperature, the mole for amount of substance and the candela for luminous intensity.
How do you convert metric units?
Multiply to go from a larger unit to a smaller one and divide to go the other way, always by a power of ten. So 4 kilometers is 4,000 meters, and 250 centimeters is 2.5 meters.
What is the difference between the metric system and SI?
SI, the International System of Units, is the modern form of the metric system, set up in 1960. In everyday speech the two names mean the same thing.
Which is bigger, a centimeter or a millimeter?
A centimeter: one centimeter is 10 millimeters, and 1,000 millimeters make a meter.