life·​time | \ˈlīf-ˌtīm \

Definition of lifetime 

(Entry 1 of 2)

1a : the duration of the existence of a living being (such as a person or an animal) or a thing (such as a star or a subatomic particle)

b : life sense 12

2 : an amount accumulated or experienced in a lifetime a lifetime of regrets



Definition of lifetime (Entry 2 of 2)

1 : lifelong

2 : of long duration or continuance lifetime legislation

3 : measured or achieved over the span of a career a baseball player's lifetime batting average

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Synonyms for lifetime

Synonyms: Noun

continuance, date, duration, life, life span, run, standing, time

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Examples of lifetime in a Sentence


a lifetime spent traveling the world It would have taken me a lifetime to read all those books. Childhood seems a lifetime ago now! a chemical with a lifetime of only a few minutes the lifetime of a planet
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Recent Examples on the Web: Noun

The long lifetime for version 1809 makes this kind of partial, phased release much less appealing, as those people using it will forever be stuck with the partial feature, at least until the next LTSC release is made in 2021. Peter Bright, Ars Technica, "Microsoft pulls Windows Sets “tabbed windows” feature from next release," 27 June 2018 Based on 2017 data, women could be expected to bear 1.43 children on average in their lifetimes. Peter Landers, WSJ, "Don’t Want Kids? That’s All Right, Japanese Prime Minister Says," 27 June 2018 Now, however, the U.S. National Institutes of Health estimates that 14.4 million Americans will be diagnosed in their lifetimes with PTSD. John Schmid, Milwaukee Journal Sentinel, "Help wanted: Trauma-focused social workers to stop downward spiral in Milwaukee," 4 June 2018 For better or for worse, most of us have never, and probably will never see a Komodo dragon in our lifetimes. Madeleine Aggeler, The Cut, "Sharon Stone Has (Second) Run-in With a Komodo Dragon," 4 June 2018 These includes a multimillion-dollar investment to send scientists to study Thwaites Glacier in West Antarctica - the single greatest threat for fast-rising seas in our lifetimes, several scientific experts said. The Washington Post,, "In internal memo, White House considered whether to simply 'ignore' federal climate research," 23 May 2018 The answers were scored and categorized based on whether the kids experienced discrimination in the last 30 days, the past year or in their lifetimes. Michael Harriot, The Root, "Study: Affluent Black Kids Suffer Higher Rates of Depression Because ... You Guessed It: Racism," 15 May 2018 The photos triggered her memories of her lifetime of abuse. Ryan W. Miller, USA TODAY, "Daughter kills dad after finding his child porn collection. She buried her secret for 12 years," 13 July 2018 General Franco led the Nationalists to victory over the Republicans, then taking his place as the head of government for the rest of his lifetime until his death in 1975. Joseph Zeballos-roig, The New Republic, "How to Dig Up a Dictator," 11 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lifetime.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of lifetime


13th century, in the meaning defined at sense 1a


1834, in the meaning defined at sense 1

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Statistics for lifetime

Last Updated

9 Nov 2018

Look-up Popularity

Time Traveler for lifetime

The first known use of lifetime was in the 13th century

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More Definitions for lifetime



English Language Learners Definition of lifetime

: the time during which a person is alive

: a very long time

: the time during which something lasts or is useful


life·​time | \ˈlīf-ˌtīm \

Kids Definition of lifetime

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Comments on lifetime

What made you want to look up lifetime? Please tell us where you read or heard it (including the quote, if possible).


something that serves to warn or remind

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