duffer vs slummock

duffer

noun
  • An incompetent, indolent, or clumsy person. 

  • Any of various nymphalid butterflies of the genus Discophora. 

  • A player having little skill, especially a golfer who duffs. 

  • A racing pigeon that does not perform well. 

  • A cow that does not produce milk. 

slummock

noun
  • A slovenly person 

verb
  • To behave awkwardly or clumsily 

  • To behave lazily or indolently 

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