lifetime
Americannoun
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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:
Moreover, the filing claims that the new entity reneged on a number of promises, including that members would keep their lifetime voting rights as well as their lifetime tickets to the award show.
From Los Angeles Times ● Jul. 28, 2026
In 2011 a commission headed by the economist Andrew Dilnot proposed a lifetime cap of £35,000.
From BBC ● Jul. 27, 2026
Most working Americans do not plan to wait until age 70 to claim, despite reducing their lifetime benefits by claiming the benefit sooner.
From MarketWatch ● Jul. 23, 2026
How do I stay engaged over a lifetime?
From The Wall Street Journal ● Jul. 23, 2026
“I had spent a lifetime learning about plants and what they could do to heal.”
From "Nory Ryan’s Song" by Patricia Reilly Giff
Developing superintelligence will be the most profound technological advance we will see in our lifetimes.
From The Wall Street Journal ● Jul. 28, 2026
As researchers develop even purer magnetic materials, magnon lifetimes may continue to improve.
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
However, among graduate men with low prior attainment, around four in 10 can expect to be worse-off financially over their lifetimes than if they had not gone to university.
From BBC ● Jun. 25, 2026
As if I hadn’t already cried enough for two lifetimes.
From "A Mango-Shaped Space" by Wendy Mass
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.
