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
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 one of those treatment sessions.
—
Wesley Stenzel, EW.com, 25 June 2024
This rare earth metal was preferred for being gentler on the kidneys and having a longer half-life, benefiting manufacturing and logistics.
—Elie Dolgin, Ars Technica, 21 June 2024
But the story doesn’t end there, for the compassion for asylum seekers generated by Kurdi’s image proved to have a short half-life.
—Vox Staff, Vox, 3 June 2024
To conduct and study chemical reactions, researchers require an element with a half-life of at least half a second.
—Stephanie Pappas, Scientific American, 14 May 2024
Tweets in certain languages had a shorter half-life than others, with 49% of Turkish tweets and 42% of Arabic tweets disappearing over the study period.
—Rob Pegoraro, PCMAG, 20 May 2024
This could be the myth of Blackness itself, that it is never permitted to grow up, to sound too bitter, forever young and inchoate, never atrophying past the dazzling tones of entertainment so that all the world accepts wholeheartedly of Black life is its half-life.
—Harmony Holiday, Los Angeles Times, 19 Mar. 2024
The report noted that Perry had been receiving ketamine infusion treatment but said the ketamine in his system could not have been from one of those sessions due to its short half-life.
—Wesley Stenzel, EW.com, 9 Jan. 2024
In addition to the four major PFAS, there are hundreds, if not thousands, of replacement chemicals that have a shorter half-life than the major PFAS.
—Claire Bugos, Verywell Health, 29 Jan. 2024
Wesley Stenzel, EW.com, 25 June 2024
This rare earth metal was preferred for being gentler on the kidneys and having a longer half-life, benefiting manufacturing and logistics.
—Elie Dolgin, Ars Technica, 21 June 2024
But the story doesn’t end there, for the compassion for asylum seekers generated by Kurdi’s image proved to have a short half-life.
—Vox Staff, Vox, 3 June 2024
To conduct and study chemical reactions, researchers require an element with a half-life of at least half a second.
—Stephanie Pappas, Scientific American, 14 May 2024
Tweets in certain languages had a shorter half-life than others, with 49% of Turkish tweets and 42% of Arabic tweets disappearing over the study period.
—Rob Pegoraro, PCMAG, 20 May 2024
This could be the myth of Blackness itself, that it is never permitted to grow up, to sound too bitter, forever young and inchoate, never atrophying past the dazzling tones of entertainment so that all the world accepts wholeheartedly of Black life is its half-life.
—Harmony Holiday, Los Angeles Times, 19 Mar. 2024
The report noted that Perry had been receiving ketamine infusion treatment but said the ketamine in his system could not have been from one of those sessions due to its short half-life.
—Wesley Stenzel, EW.com, 9 Jan. 2024
In addition to the four major PFAS, there are hundreds, if not thousands, of replacement chemicals that have a shorter half-life than the major PFAS.
—Claire Bugos, Verywell Health, 29 Jan. 2024
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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 Jul. 2024.
Copy CitationMedical Definition
half-life
noun
ˈhaf-ˌlīf 
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 days—The Journal of the American Medical Association
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