autonym vs initials

autonym

noun
  • An infraspecific name in which the specific epithet is repeated. 

  • A name used by a group or category of people to refer to themselves or their language, as opposed to a name given to them by other groups. 

  • A work published under the author's true name. 

  • The true name of a person or other entity, especially an author. 

initials

noun
  • An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram 

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