dyadic vs twinfold

dyadic

adj
  • having an arity of two (taking two arguments or operands) 

  • Pertaining to a dyad, the number two; of two parts or elements. 

  • Pertaining to the physical sex of a person who is exactly male or female in genetics, anatomy and hormone levels; not intersex. 

noun
  • The sum of two or more dyads 

twinfold

adj
  • Synonym of twofold 

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