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
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.
One study Shain co-authored found that tanning beds accelerate DNA mutations in parts of the body not typically exposed to the sun, leading to a nearly threefold increase in indoor tanners’ lifetime melanoma risk.
From Los Angeles Times • May 6, 2026
They will not increase the number of bands or rates over the lifetime of the next parliament, and will aim to make the system simpler.
From BBC • May 5, 2026
I have enough retirement income and Social Security to see me through my lifetime.
From MarketWatch • May 5, 2026
She was a merchandising consultant and sat on the company’s board until 2009, when she became an honorary lifetime director.
From The Wall Street Journal • May 4, 2026
I’d probably read more newspapers in one week than he’d read in his entire lifetime!
From "The Detective's Assistant" by Kate Hannigan
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.
