recurring vs recursion

recurring

noun
  • A recurrence; a coming round again. 

adj
  • Of a decimal: having a set of digits that is repeated indefinitely. 

  • Happening or occurring frequently, with repetition. 

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 recurring and recursion occurred in a corpus of books? (source: Google Ngram Viewer )