abnormal vs exceptional

abnormal

adj
  • Of or pertaining to that which is irregular, in particular, behaviour that deviates from norms of social propriety or accepted standards of mental health. 

  • Not conforming to rule or system; deviating from the usual or normal type. 

noun
  • A person or object that is not normal. 

exceptional

adj
  • Forming an exception; not ordinary; uncommon; rare. 

  • Corresponding to something of lower dimension under a birational correspondence. 

  • Better than the average; superior due to exception or rarity. 

noun
  • An exception, or something having an exceptional value 

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