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[lahyf-tahym] /ˈlaɪfˌtaɪm/
the time that the life of someone or something continues; the term of a life:
peace within our lifetime.
Physics. mean life.
for the duration of a person's life:
He has a lifetime membership in the organization.
Origin of lifetime
1175-1225; Middle English liftime. See life, time Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2016.
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Examples from the Web for lifetime
Contemporary Examples
Historical Examples
  • I sincerely trust the young man has not suffered a lifetime for the act.

    Between the Lines Henry Bascom Smith
  • All the emotion of his lifetime seemed crowded into that moment.

    A Prisoner of Morro Upton Sinclair
  • Students have made the study of its windows a lifetime enthusiasm.

    How France Built Her Cathedrals Elizabeth Boyle O'Reilly
  • My father was a paper-maker, and lived all his lifetime in the town.

    A Soldier's Life Edwin G. Rundle
  • Have you not spent a lifetime of regret to atone for a moment of folly?

    Cape of Storms Percival Pollard
British Dictionary definitions for lifetime


  1. the length of time a person or animal is alive
  2. (as modifier): a lifetime supply
the length of time that something functions, is useful, etc
(physics) the average time of existence of an unstable or reactive entity, such as a nucleus, excited state, elementary particle, etc; mean life
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for lifetime

also life-time, early 13c., from life (n.) + time (n.). One word from 19c. Old English had lifdæg in same sense, literally "life day."

Online Etymology Dictionary, © 2010 Douglas Harper
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lifetime in Medicine

lifetime life·time (līf'tīm')

  1. The period of time during which an individual is alive.

  2. The period of time during which property, an object, a process, or a phenomenon exists or functions.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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