VERB (4)

1. retire and pension (someone) because of age or physical inability;

2. declare to be obsolete;

3. become obsolete;

4. retire or become ineligible because of old age or infirmity;

The Collaborative International Dictionary of English v.0.48:

Superannuate \Su`per*an"nu*ate\, v. t. [imp. & p. p.
   Superannuated; p. pr. & vb. n. Superannuating.] [Pref.
   super- + L. annus a year.]
   1. To impair or disquality on account of age or infirmity.
      --Sir T. Browne.
      [1913 Webster]

   2. To give a pension to, on account of old age or other
      infirmity; to cause to retire from service on a pension.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Superannuate \Su`per*an"nu*ate\, v. i.
   To last beyond the year; -- said of annual plants. [Obs.]
   --Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

superannuate
    v 1: retire and pension (someone) because of age or physical
         inability
    2: declare to be obsolete
    3: become obsolete
    4: retire or become ineligible because of old age or infirmity