etymon vs radix

etymon

noun
  • Meaning as derived and conveyed thereby: The literal meaning of a term according to its origin, which may differ from its usual meaning when the latter relies on idiomatic conventions that are not conveyed by the term alone (that is, they must be known in other ways, such as experience, training, education, or dictionary lookup). 

  • The original or earlier form of an inherited or borrowed word, affix, or morpheme either from an earlier period in a language's development, from an ancestral language, or from a foreign language. 

radix

noun
  • A primitive word, from which other words may be derived. 

  • A root. 

  • The number of distinct symbols used to represent numbers in a particular base, as ten for decimal. 

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