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.
To put that instability into context, I was 27 years old before I was on to the fourth prime minister of my lifetime, Gordon Brown in 2007.
From BBC • May 12, 2026
It's exceedingly rare for the White House to exert open pressure on the nine-judge panel, who are appointed to lifetime terms by the president and confirmed by Congress.
From Barron's • May 11, 2026
Because methane has a shorter atmospheric lifetime, reducing methane pollution could produce climate benefits relatively quickly.
From Science Daily • May 10, 2026
The difference between guessing and modeling can add up to hundreds of thousands of dollars over a lifetime.
From MarketWatch • May 8, 2026
He had, almost within grasp, the story of a lifetime.
From "Most Dangerous: Daniel Ellsberg and the Secret History of the Vietnam War" by Steve Sheinkin
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.
