impugn vs permit

impugn

verb
  • To verbally assault, especially to argue against an opinion, motive, or action; to question the truth or validity of. 

permit

noun
  • A pompano of the species Trachinotus falcatus. 

  • An artifact or document rendering something allowed or legal. 

  • A learner's permit. 

verb
  • To allow (something) to happen, to give permission for. 

  • To allow for, to make something possible. 

  • To allow, to admit (of). 

  • To grant formal authorization for (something). 

  • To attempt to obtain or succeed in obtaining formal authorization for (something). 

  • To allow (someone) to do something; to give permission to. 

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