involve vs need

involve

verb
  • To cause or engage (someone or something) to participate or to become connected or implicated. 

  • To take in; to gather in; to mingle, blend or merge. 

  • To comprise or include; to have as a related part. 

  • To complicate or make intricate. 

  • To envelop, enfold, entangle. 

need

verb
  • To be obliged or required (to do something). 

  • To be required; to be necessary. 

  • To want strongly; to feel that one must have something. 

  • To have an absolute requirement for. 

noun
  • Lack of means of subsistence; poverty; indigence; destitution. 

  • A requirement for something; something needed. 

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