What does longevity mean?

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From our dictionary:

lon•gev•i•ty

Pronunciation: (lon-jev'i-tE, lôn-), [key]
n.
1. a long individual life; great duration of individual life: Our family is known for its longevity.
2. the length or duration of life: research in human longevity.
3. length of service, tenure, etc.; seniority: promotions based on longevity.