frequency vs recursion

frequency

noun
  • The property of occurring often rather than infrequently. 

  • The quotient of the number of times n a periodic phenomenon occurs over the time t in which it occurs: f=n/t. 

  • number of times an event occurred in an experiment (absolute frequency) 

  • The rate of occurrence of anything; the relationship between incidence and time period. 

recursion

noun
  • The act of recurring. 

  • The act of defining an object (usually a function) in terms of that object itself. 

  • The invocation of a procedure from within itself. 

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