The Collaborative International Dictionary of English v.0.48:

Longevity \Lon*gev"i*ty\, n. [L. longaevitas. See Longevous.]
   Long duration of life; length of life.
   [1913 Webster]

         The instances of longevity are chiefly amongst the
         abstemious.                              --Arbuthnot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

longevity
    n 1: duration of service; "her longevity as a star"; "had
         unusual longevity in the company" [syn: longevity,
         length of service]
    2: the property of being long-lived [syn: longevity,
       seniority]

The Devil's Dictionary (1881-1906):

LONGEVITY, n.  Uncommon extension of the fear of death.