frustrate vs obstruct

frustrate

verb
  • To hinder or thwart. 

  • To cause stress or annoyance. 

  • To disappoint or defeat; to vex by depriving of something expected or desired. 

adj
  • ineffectual; useless; fruitless. 

obstruct

verb
  • To impede, retard, or interfere with; hinder. 

  • To get in the way of so as to hide from sight. 

  • To block or fill (a passage) with obstacles or an obstacle. See synonyms at block. 

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