qualify vs trouble

qualify

verb
  • To give individual quality to; to modulate; to vary; to regulate. 

  • To certify or license someone for something. 

  • To throw and catch each object at least twice. 

  • To compete successfully in some stage of a competition and become eligible for the next stage. 

  • To make someone, or to become competent or eligible for some position or task. 

  • To modify, limit, restrict or moderate something; especially to add conditions or requirements for an assertion to be true. 

  • To describe or characterize something by listing its qualities. 

noun
  • An instance of throwing and catching each prop at least twice. 

trouble

verb
  • In weaker sense: to bother or inconvenience. 

  • To mentally distress; to cause (someone) to be anxious or perplexed. 

  • To worry; to be anxious. 

  • To take pains to do something. 

noun
  • A difficulty, problem, condition, or action contributing to such a situation. 

  • A fault or interruption in a stratum. 

  • A malfunction. 

  • A violent occurrence or event. 

  • Efforts taken or expended, typically beyond the normal required. 

  • Liability to punishment; conflict with authority. 

  • Wife. Clipping of trouble and strife. 

  • A distressing or dangerous situation. 

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