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

If ancient Greece gave us classical architecture and democracy, modern life gave us the most distinctive American architectural creation, the skyscraper.

From The Wall Street Journal • Jun. 27, 2026

Chronic fatigue has become increasingly common in modern life as people juggle heavier workloads and less downtime.

From Science Daily • May 29, 2026

That could produce difficulties for the cloned animals and for modern life, including the possible revival of prehistoric pathogens for which humankind has no defense.

From Los Angeles Times • May 21, 2026

More fundamentally, the “just turn it off” logic begins collapsing once you think seriously about what modern life requires.

From Slate • May 20, 2026

So to return to Troy McClure and his terrible relevance to modern life, ethos is behind every celebrity endorsement you ever see on television.

From "Words Like Loaded Pistols" by Sam Leith