Synonyms

mean life

American

noun

Physics.

the average time that an unstable particle or nucleus survives before it decays.
decay time.

mean life British

noun

τ. physics the average time of existence of an unstable or reactive entity, such as a nucleus, elementary particle, charge carrier, etc; lifetime. It is equal to the half-life divided by 0.693 15

"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

Example Sentences

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mean life

One example is extensive, independent testing to ensure the effectiveness and reliability of critical systems, which can mean life or death for servicemembers.

From The Wall Street Journal ● Apr. 16, 2026

This does not mean life has been confirmed on Mars.

From Science Daily ● Feb. 12, 2026

“Really, it can mean life or death in a lot of cases where you don’t get the information, where it’s not translated in a city and county like Los Angeles.”

From Los Angeles Times ● May 26, 2025

“That is hugely significant, because if that happens twice in our solar system, it could mean life is really common,” he says.

From BBC ● Oct. 13, 2024

That could mean life and death on the upper reaches of the Rhoyne, Yandry claimed.

From "A Dance with Dragons" by George R. R. Martin

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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023