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.
If she starts taking the survivor’s benefit now and lives to age 95, she would miss out on approximately $128,000 in benefits over her lifetime.
From MarketWatch • May 26, 2026
The chip also incorporates high-speed sensors capable of measuring photon lifetime with extremely high temporal precision.
From Science Daily • May 26, 2026
“When tribal healthcare was on the line, he was there. This experience comes from a lifetime of public service, not a checkbook.”
From Los Angeles Times • May 26, 2026
In a breezy, sun-soaked 90 minutes, Romvari excavates a lifetime of knotted, intergenerational trauma — a phrase that almost feels too heavy and too burdened by cryptic implications, given how this movie explores it.
From Salon • May 25, 2026
Although these questions might seem to be simple, they reflect a depth of music knowledge garnered throughout a lifetime of cultural exposure to music.
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.
