x_{1 }= t_{1} is the elapsed time required for decaying/diminishing/reducing/shrinking population x_{2 }= g_{1} to decrease in number by a factor of exactly/approximately 1/(x_{3)} from that which is considered to be the initial population size, where x_{3} [li; default: 1] is a positive real number, according to standard/under condition/by model/in experiment x_{4}; x_{1} is the (x_{3^(-1))}-th-life of population/sample x_{2}; the (approximate) one-x_{3}-th-ing/(x_{3)}-fold decrease(/increase) of population x_{2} takes approximately x_{1} (time).

The experimental gismu xonba is used in the veljvo of this word. Many of the veljvo terbri of this word can be derived from those which are present. This word may refer to a duration that is statistical (for large samples, the average time required for half of the population to probably disappear/become invalid), ideal (guaranteed rather than statistical), or experimental (in a given trial, some number was recorded on a stopwatch when the count decreased by half). This word is analogous not only to half-life (and means it exactly if x_{3} is filled by 2) but also to doubling time (and means it exactly if x_{3} is filled by 1/2). See also: grixabybi'otei, gritezdybi'otei.

- gritezdybi'otei
- x
_{1 }= t_{1}is the elapsed time required for decaying/diminishing/reducing/shrinking population x_{2 }= g_{1}to decrease in number by a factor of exactly/approximately 1/e^(x_{3)}from that which is considered to be the initial population size, where e is the natural exponential base and x_{3}[li; default: 1] is a real number, according to standard/under condition/by model/in experiment x_{4}; x_{1}is the one-(e^(x_{3))}-th-life of population/sample x_{2}; the (approximate) (x_{3)}-th one-e-th-ing/e-fold decrease(/increase) of population x_{2}takes approximately x_{1}(time). - grixabybi'otei
- x
_{1 }= t_{1}is the elapsed time required for decaying/diminishing/reducing/shrinking population x_{2 }= g_{1}to decrease in number by a factor of exactly/approximately half according to standard/under condition/by model/in experiment x_{3}; x_{1}is the half-life of population/sample x_{2}; the (approximate) halving of population x_{2}takes approximately x_{1}(dimensionful number: time).