infix vs interject

infix

verb
  • To instill. 

  • To insert a morpheme inside an existing word. 

noun
  • A morpheme that always appears between other morphemes in a word, such as -i- and -o- in English (i.e. an interfix). 

  • A morpheme inserted inside an existing word, such as -bloody- in English. 

interject

verb
  • To interpose oneself; to intervene. 

  • To insert something between other things. 

  • To say as an interruption or aside. 

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