lifetime
n.-
1 duration of life (n.) B1 Intermediatethe period of time during which someone is alive.
the duration of a person's life from birth to death.
ExampleHe saw many incredible changes in technology during his lifetime.
ExampleThe scientist dedicated her entire lifetime to researching rare tropical plants in the hope of finding new medicinal compounds.
UsageOften used with possessive adjectives like 'my lifetime' or 'her lifetime'.
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2 functional period (n.) B2 Upper Intermediatethe length of time that a machine or product stays useful.
the period during which a physical object or system remains functional or relevant.
ExampleThe battery has a lifetime of about three years before it needs replacing.
ExampleEngineers are working to extend the operational lifetime of the satellite to ensure it can continue transmitting data for another decade.
UsageCommonly used in technical or consumer contexts regarding product durability.
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3 a very long time (n.) B2 Upper Intermediate Informala very long period of time, often used when you are waiting for something.
a hyperbolic reference to an exceptionally long duration of time.
ExampleIt felt like a lifetime before the doctor finally came out to speak to us.
ExampleIn the fast-moving world of digital fashion, six months can feel like a lifetime for a brand trying to stay relevant.
UsageUsually appears in the singular with the indefinite article 'a'.
Teacher's tipRemind students that this is an exaggeration; it doesn't literally mean a person's whole life.
From Middle English lyftyme, equivalent to life + time. Cognate with Icelandic líftími (“lifetime”). Compare also Saterland Frisian Lieuwendstied, Dutch leeftijd and levenstijd, German Low German Levenstied, German Lebenszeit, Danish livstid, Swedish livstid.