pull off vs undertake

pull off

verb
  • To turn off a road (onto the side of the road, or onto another road). 

  • To begin moving and then move away; to pull away. 

  • To masturbate. 

  • To remove by pulling. 

  • To achieve; to succeed at something difficult. 

undertake

verb
  • To pass a slower moving vehicle on the curbside rather than on the side closest to oncoming traffic. 

  • To commit oneself (to an obligation, activity etc.). 

  • To take upon oneself; to start, to embark on (a specific task etc.). 

noun
  • The passing of slower traffic on the curbside rather than on the side closest to oncoming traffic. 

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