feckful vs intensive

feckful

adj
  • Powerful, effective, efficient, vigorous. 

intensive

adj
  • Thorough; to a great degree; with intensity. 

  • Characterized by persistence; intent; assiduous. 

  • Serving to give force or emphasis. 

  • Demanding; requiring a great amount of work etc. 

  • Related to the need to manage life-threatening conditions by means of sophisticated life support and monitoring. 

  • Highly concentrated. 

noun
  • A form of a word with a stronger or more forceful sense than the root on which the intensive is built. 

  • A course taught intensively. 

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