demerit vs imperfection

demerit

noun
  • A quality of being inadequate; a fault; a disadvantage 

  • A mark given for bad conduct to a person attending an educational institution or serving in the army. 

  • That which one merits or deserves, either of good or ill; desert. 

imperfection

noun
  • Those qualities or features that are imperfect; the characteristic, state, or quality of being imperfect. 

  • Something that makes something else less than perfect; a blemish, impurity, error, etc. 

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