deficient vs duffer

deficient

noun
  • A person who is deficient. 

adj
  • Insufficient or inadequate in amount. 

  • Lacking something essential; often construed with in. 

  • Of a number n, Having the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n). 

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. 

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