advise vs prewarn

advise

verb
  • To give information or notice to; to inform or counsel; — with of before the thing communicated. 

  • To consider, to deliberate. 

  • To give advice to; to offer an opinion to, as worthy or expedient to be followed. 

  • To recommend; to offer as advice. 

  • To deliver judgment after a case has been reserved for further consideration. 

prewarn

verb
  • To warn beforehand; to forewarn. 

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