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

SUPERANNUATE is a 12 letter word that starts with S.

1. \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.
   
   2. To give a pension to, on account of old age or other
      infirmity; to cause to retire from service on a pension.
   
   

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