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
Drugs can have different half-lives, with some ranging from a few hours to days.
—
Phuoc Anh (anne) Nguyen, Pharmd, Ms, Verywell Health, 17 July 2024
Introduction Norman and colleagues published a reinvestigation of this half-life in Physical Review C in late May.
—Quanta Magazine, 12 July 2024
This rare earth metal was preferred for being gentler on the kidneys and having a longer half-life, benefiting manufacturing and logistics.
—Discover Magazine, 8 July 2024
Mathematical modeling indicated more than 10% of the proteins had a half-life—the time for 50% of the molecules to decay—of more than 100 days, roughly 13% of a mouse’s life span.
—science.org, 3 July 2024
See all Example Sentences for half-life 
Phuoc Anh (anne) Nguyen, Pharmd, Ms, Verywell Health, 17 July 2024
Introduction Norman and colleagues published a reinvestigation of this half-life in Physical Review C in late May.
—Quanta Magazine, 12 July 2024
This rare earth metal was preferred for being gentler on the kidneys and having a longer half-life, benefiting manufacturing and logistics.
—Discover Magazine, 8 July 2024
Mathematical modeling indicated more than 10% of the proteins had a half-life—the time for 50% of the molecules to decay—of more than 100 days, roughly 13% of a mouse’s life span.
—science.org, 3 July 2024
See all Example Sentences for half-life
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“Half-life.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/half-life. Accessed 26 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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