Source : Webster's Revised Unabridged Dictionary (1913)

Lifelong \Life"long`\ (-l[o^]ng`), a. [Life + long. Cf.
   {Livelong}.]
   Lasting or continuing through life. --Tennyson.

Source : WordNet®

lifelong
     adj : continuing through life; "a lifelong friend"; "from lifelong
           habit"; "his lifelong study of Greek art" [syn: {womb-to-tomb}]