SI ajaühik, mis võrdub tseesium-133 aatomi põhiseisundi kahe ülipeene nivoo vahelisele üleminekule vastava kiirguse 9 192 631 770 perioodiga
SI base unit of time, 1/60 part of a minute of time
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 caesium-133 atom
