complication vs pitfall

complication

noun
  • A disease or diseases, or adventitious circumstances or conditions, coexistent with and modifying a primary disease, but not necessarily connected with it. 

  • A person who doesn't fit in with the main scheme of things; an interloper. 

  • The state of being complicated; intricate or confused relation of parts; complexity. 

  • The act or process of complicating. 

  • A feature beyond basic time display in a timepiece. 

pitfall

noun
  • A potential, unsuspected, hidden problem, hazard, or danger that is easily encountered but not immediately obvious. 

  • A type of trap consisting of a concealed pit in the ground, which the victim is supposed to fall into and not be able to get out from. 

  • An antipattern. 

  • Subsidence below ground in a mine, which can cause the ground level above to drop. 

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