meter [m] the
meter is the length of the path traveled by light in vacuum during
a time interval of 1/299 792 458 of a second.
the kilogram is the unit of mass; it is equal to the mass of the
international prototype of the kilogram.
second [s] the
second is the duration of 9 192 631 770 periods of the radiation
corresponding to the transition between the two hyperfine levels of
the ground state of the cesium 133 atom.
ampere [A] the
ampere is that constant current which, if maintained in two straight
parallel conductors of infinite length, of negligible circular
cross-section, and placed 1 meter apart in vacuum, would produce
between these conductors a force equal to 2 x 10-7 Newton
per meter of length.
kelvin [K] the
Kelvin, unit of thermodynamic temperature, is the fraction 1/273.16
of the thermodynamic temperature of the triple point of water.
mole [mol] the
mole is the amount of substance of a system which contains as many
elementary entities as there are atoms in 0.012 kilogram of carbon
the candela is the luminous intensity, in a given direction, of a
source that emits monochromatic radiation of frequency 540 x 1012
hertz and that has a radiant intensity in that direction of 1/683
watt per steradian.