lifetime
Americannoun
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lifetimes
plural
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the time that the life of someone or something continues; the term of a life.
peace within our lifetime.
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Physics. mean life.
adjective
noun
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the length of time a person or animal is alive
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( as modifier )
a lifetime supply
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the length of time that something functions, is useful, etc
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physics the average time of existence of an unstable or reactive entity, such as a nucleus, excited state, elementary particle, etc; mean life
Other Word Forms
Noun Inflected Forms
Etymology
Origin of lifetime
First recorded in 1175–1225, lifetime is from the Middle English word liftime. See life, time
Explanation
A lifetime is the entire length of time a person or other living thing is alive. After a famous actor dies, she may be fondly remembered for a lifetime of great movie roles. Things that take up most of the duration of a person's life are often described using the word lifetime, like a terrible driver's lifetime ban on holding a driver's license, or a lifetime achievement award for all of your accomplishments. You can also talk about the lifetime of an object, or the length of time it's useful, and use lifetime figuratively, to mean "a very long time."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Investments could drastically change the ultimate amount a person has to spend over the rest of their lifetime, especially as Americans are living longer and spending two or even three or more decades in retirement.
From MarketWatch ● Aug. 7, 2026
That hardly diminishes a lifetime spent largely out of the spotlight as a dedicated public servant.
From The Wall Street Journal ● Aug. 7, 2026
"We're very unlikely to meet one, at least in our lifetime."
From Science Daily ● Aug. 6, 2026
“At least in my lifetime, I haven’t seen so many people organize for one effort.”
From Slate ● Aug. 6, 2026
“Twice in my lifetime I have heard travelers speak of this rat. He bears a name that a fox would be afraid to whisper in the darkness of midnight. Cluny the Scourge!”
From "Redwall" by Brian Jacques
Researchers say amphibians provide a window into the past because they don’t travel far during their lifetimes and are sensitive to climate change.
From Los Angeles Times ● Aug. 7, 2026
With only a handful of lyrics, she revisits a million lifetimes replete with monumental change and insights only an artist of her caliber could convey.
From Salon ● Jul. 8, 2026
By increasing magnon lifetimes to as much as 18 microseconds, the researchers turned these once fleeting signals into long-lasting carriers of quantum information.
From Science Daily ● Jul. 2, 2026
Labor’s share of income, which is about 60% now, will almost definitely go below 50% in our lifetimes.
From The Wall Street Journal ● Jun. 28, 2026
Since such stars with higher temperatures and pressures run rapidly through their store of nuclear fuel, their lifetimes are much shorter than the Sun’s.
From "Cosmos" by Carl Sagan
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
