retention vs tenure

retention

noun
  • The act of retaining or something retained 

  • The portion of a potential damange that must be paid for by the holder of an insurance policy. 

  • The act or power of remembering things 

  • The involuntary withholding of urine and faeces 

  • A memory; what is retained in the mind 

  • The length of time an individual remains in treatment 

  • The right to withhold a debt, or of retaining property until a debt due to the person claiming the right is duly paid; a lien. 

tenure

noun
  • A status of possessing a thing or an office; an incumbency. 

  • A period of time during which something is possessed. 

  • A right to hold land under the feudal system. 

  • A status of having a permanent post with enhanced job security within an academic institution. 

verb
  • To grant tenure, the status of having a permanent academic position, to (someone). 

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