problem vs weakness

problem

noun
  • A difficulty that has to be resolved or dealt with. 

  • A puzzling circumstance. 

  • A set of moves required to complete a climb. 

  • A question to be answered, schoolwork exercise. 

  • Objection. 

  • Difficulty in accepting or understanding or refusal to accept or understand. 

adj
  • Causing a problem; problematic; troublesome. 

  • Difficult to train or guide; unruly. 

weakness

noun
  • An inadequate quality; fault 

  • The condition of being weak. 

  • A special fondness or desire. 

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