Definition of lifetime
- a lifetime of regrets
a lifetime spent traveling the world
It would have taken me a lifetime to read all those books.
Childhood seems a lifetime ago now!
a chemical with a lifetime of only a few minutes
the lifetime of a planet
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lifetime.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
: the time during which a person is alive
: a very long time
: the time during which something lasts or is useful
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