metathesis vs permutation

metathesis

noun
  • The breaking and reforming of double bonds in olefins in which substituent groups are swapped. 

  • The double decomposition of inorganic salts. 

  • The transposition of letters, syllables or sounds within a word, such as in ask as /æks/. 

permutation

noun
  • A transformation of a set's prime form, by applying one or more of certain operations, specifically, transposition, inversion, and retrograde. 

  • One of the ways something exists, or the ways a set of objects can be ordered. 

  • An ordering of a finite set of distinct elements. 

  • A one-to-one mapping from a finite set to itself. 

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