etymon vs source

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. 

source

noun
  • Spring; fountainhead; wellhead; any collection of water on or under the surface of the ground in which a stream originates. 

  • A reporter's informant. 

  • Source code. 

  • The name of one terminal of a field effect transistor (FET). 

  • The person, place, or thing from which something (information, goods, etc.) comes or is acquired. 

verb
  • To obtain or procure: used especially of a business resource. 

  • To find information about (a quotation)'s source (from which it comes): to find a citation for. 

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