internal organ vs offal

internal organ

noun
  • An organ, such as the heart or colon, that is entirely within the confines of the body. 

offal

noun
  • The internal organs of an animal, used as food. 

  • That which is thrown away as worthless or unfit for use; refuse; rubbish. 

  • A dead body; carrion. 

  • A by-product of the grain milling process, which may include bran, husks, etc. 

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