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]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "longevity":
   abidingness, advanced age, advanced years, age, age of retirement,
   an incurable disease, anility, animal spirits, animate existence,
   animation, antiquity, being alive, birth, caducity, constancy,
   continuance, debility, decline of life, declining years,
   decrepitude, defeat of time, defiance of time, diuturnity, dotage,
   durability, durableness, duration, eld, elderliness, endurance,
   existence, feebleness, green old age, hale old age, haleness,
   hardiness, having life, heartiness, hoary age, immortality,
   infirm old age, infirmity, infirmity of age, lastingness, life,
   lifetime, liveliness, living, long life, long standing,
   long-lastingness, long-livedness, lustiness, maintenance, old age,
   oldness, pensionable age, perdurability, perennation, permanence,
   perpetuity, persistence, ricketiness, ripe old age, robustness,
   ruggedness, second childhood, senectitude, senility,
   senior citizenship, spriteliness, stability, standing,
   steadfastness, strength, superannuation, survival, survivance,
   the downward slope, the golden years, vale of years, viability,
   vigor, vigorousness, vitality, vivacity, white hairs



The Devil's Dictionary (1881-1906):

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