relieve vs undertake

relieve

verb
  • To release (someone) from or of a difficulty, unwanted task, responsibility etc. 

  • To ease (someone, a part of the body etc.) or give relief from physical pain or discomfort. 

  • To ease (a person, person's thoughts etc.) from mental distress; to stop (someone) feeling anxious or worried, to alleviate the distress of. 

  • To free (someone) from debt or legal obligations; to give legal relief to. 

  • To alleviate (pain, distress, mental discomfort etc.). 

  • To urinate or defecate. 

  • To ease one's own desire to orgasm, often through masturbation to orgasm. 

  • To bring military help to (a besieged town); to lift the siege on. 

  • To free (someone) from their post, task etc. by taking their place. 

  • To provide comfort or assistance to (someone in need, especially in poverty). 

undertake

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

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

  • 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 relieve and undertake occurred in a corpus of books? (source: Google Ngram Viewer )