call back vs unsay

call back

verb
  • To request someone's return. 

  • To telephone someone again at a more convenient time. 

  • To return to a shop or residence one has previously visited. 

noun
  • Request for a second interview or audition, following a successful initial interview. 

unsay

verb
  • To withdraw, retract (something said). 

  • To cause something not to have been said; to make it so that one never said something (since this is physically impossible, usually in the subjunctive). 

  • I wish I could unsay that. 

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