K (thousand)
An informal abbreviation for one thousand, as in $5K = $5,000.
Kelvin scale
A temperature scale that starts at absolute zero, the lowest possible temperature. 0 K = −273.15 °C, and each kelvin is the same size as one degree Celsius.
Key
The part of a graph, pictograph or map that explains what the symbols or colors mean; also called a legend.
kg
The abbreviation for kilogram.
Kilo-
A metric prefix meaning one thousand.
Kilobyte
A unit of digital storage equal to 1,000 bytes. In computing it is sometimes used for 1,024 bytes, which is officially called a kibibyte (KiB).
Kilogram
The base unit of mass in the metric system, equal to 1000 grams. One liter of water has a mass of about 1 kilogram.
Kiloliter
A metric unit of capacity equal to 1000 liters, the volume of a cube 1 meter on each side.
Kilometer
A metric unit of length equal to 1000 meters, or about 0.62 miles.
Kilowatt-hour
A unit of energy equal to using 1 kilowatt of power for 1 hour, used on electricity bills.
Kite
A quadrilateral with two pairs of equal adjacent sides. Its diagonals are perpendicular.
kL
The abbreviation for kiloliter.
km
The abbreviation for kilometer.
km/h
Kilometers per hour, a unit of speed giving how many kilometers are traveled in one hour.
km²
The abbreviation for square kilometer, the area of a square 1 km on each side. It equals 1,000,000 square meters.
Knot
A unit of speed used at sea and in the air, equal to 1 nautical mile per hour, about 1.852 km/h or 1.151 mph.