The Collaborative International Dictionary of English v.0.48:

Age \Age\, v. i. [imp. & p. p. Aged; p. pr. & vb. n. Aging.]
   To grow aged; to become old; to show marks of age; as, he
   grew fat as he aged.
   [1913 Webster]

         They live one hundred and thirty years, and never age
         for all that.                            --Holland.
   [1913 Webster]

         I am aging; that is, I have a whitish, or rather a
         light-colored, hair here and there.      --Landor.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Aging \Ag"ing\, n.
   the process by which objects or materials acquire desirable
   qualities by being left undisturbed for some time under
   specific conditions. It is used mostly for foods snd
   beverages, but also for other materials. [Also spelled
   ageing.]
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

aging
    adj 1: growing old [syn: aging, ageing, senescent]
    n 1: acquiring desirable qualities by being left undisturbed for
         some time [syn: ripening, aging, ageing]
    2: the organic process of growing older and showing the effects
       of increasing age [syn: aging, ageing, senescence]