mean life

American  

noun

Physics.

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

2. decay time.

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mean life British  

noun

1.  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

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Example Sentences

See Examples For:

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

“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

“It could mean life or death,” McDuffie said.

From Seattle Times ● May 19, 2024

Because pinpointing a food allergy could mean life or death, an accurate diagnosis is critical.

From Science Daily ● Nov. 7, 2023

Still, Nye was glad to have seen it; each item—the palliatives for sore gums, the greasy Honolulu pillow—gave him a clearer impression of the owner and his lonely, mean life.

From "In Cold Blood" by Truman Capote