flabbergast vs take aback

flabbergast

verb
  • To overwhelm with bewilderment; to amaze, confound, or stun, especially in a ludicrous manner. 

noun
  • An awkward person. 

  • Overwhelming confusion, shock, or surprise. 

take aback

verb
  • To surprise or shock; to discomfit. 

  • Of a ship: to catch it with the sails aback suddenly. 

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