senescence vs superannuation

senescence

noun
  • The state or process of ageing, especially in humans; old age. 

  • Old age; accumulated damage to macromolecules, cells, tissues and organs with the passage of time. 

  • Fruit senescence, leading to ripening of fruit. 

  • Ceasing to divide by mitosis because of shortening of telomeres or excessive DNA damage. 

  • Condition when the cell ceases to divide. 

superannuation

noun
  • The condition or of being superannuated; old age or obsolescence. 

  • A retirement benefit fund, an accumulation of regular deductions from one′s wage or salary while employed and similar regular contributions from the employer, usually administered by an independent entity; a pension. 

How often have the words senescence and superannuation occurred in a corpus of books? (source: Google Ngram Viewer )