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

Ms Ming said that "life should mean life".

From BBC

“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

During natural disasters and extreme weather, employers’ choices can sometimes mean life or death, said David Michaels, a professor at the Milken Institute School of Public Health and a former assistant secretary of labor for the Occupational Safety and Health Administration.

From Los Angeles Times

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

From BBC

Collins said she was appalled to see online trolling from "armchair admirals, people who will never have to make decisions which mean life or death for their subordinates".

From BBC