half-life

noun

ˈhaf-ˌlīf How to pronounce half-life (audio)
ˈhäf-
1
: the time required for half of something to undergo a process: such as
a
: the time required for half of the atoms of a radioactive substance to become disintegrated
b
: the time required for half the amount of a substance (such as a drug, radioactive tracer, or pesticide) in or introduced into a living system or ecosystem to be eliminated or disintegrated by natural processes
2
: a period of usefulness or popularity preceding decline or obsolescence
slang usually has a short half-life

Examples of half-life in a Sentence

Recent Examples on the Web This was despite the decay half-life of cesium-137—one of the main contaminating isotopes—being about 30 years. Kate Graham-Shaw, Scientific American, 9 Oct. 2024 The autopsy report also noted that Perry had been receiving ketamine-infusion treatment around the time of his death, but because ketamine has a short half-life, the traces of the substance in his system couldn't have been from those treatment sessions. Ryan Coleman, EW.com, 3 Oct. 2024 Due to its half-life of 109 minutes, Flyrcado also can be produced at an offsite pharmacy then delivered to hospitals and imaging centers. Kevin Stankiewicz, CNBC, 30 Sep. 2024 Political statements by pop music stars usually have the cultural half-life of a firefly. Penny Abeywardena, Forbes, 13 Sep. 2024 See all Example Sentences for half-life 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'half-life.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1907, in the meaning defined at sense 1

Time Traveler
The first known use of half-life was in 1907

Dictionary Entries Near half-life

Cite this Entry

“Half-life.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/half-life. Accessed 5 Nov. 2024.

Kids Definition

half-life

noun
-ˌlīf
: the time required for half of the atoms of a radioactive substance to change composition

Medical Definition

half-life

noun
ˈhaf-ˌlīf How to pronounce half-life (audio)
ˈhȧf-
: the time required for half of something to undergo a process: as
a
: the time required for half of the atoms of a radioactive substance to become disintegrated
b
: the time required for half the amount of a substance (as a drug or radioactive tracer) in or introduced into a living system or ecosystem to be eliminated or disintegrated by natural processes
the serum half-life is about 2 daysThe Journal of the American Medical Association
Last Updated: - Updated example sentences
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