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.
The total lifetime tax-free gift allowance is now $15 million, an increase from the previous $13.99 million.
From MarketWatch • Jun. 2, 2026
In my lifetime, I’ve rarely seen such a universal level of community response to any one thing.”
From Slate • Jun. 1, 2026
The study, tracking 1.3 million professionals since 2000, indicates early-career slumps often lead to stalls affecting lifetime earnings.
From The Wall Street Journal • Jun. 1, 2026
He also ran a wind-aided 20.51 in the 200 at the section finals, another lifetime best.
From Los Angeles Times • May 30, 2026
Using a clear, clean, straight head voice rather than chest voice will help to avoid this, and will strengthen a child’s vocal musculature for a lifetime of excellent singing.
From "Music and the Child" by Natalie Sarrazin
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.
