threefold vs tridem

threefold

noun
  • An algebraic variety of dimension 3. 

adj
  • triple 

  • three times as great 

adv
  • by a factor of three 

verb
  • To make threefold; to triple. 

tridem

noun
  • An arrangement of three objects arranged one behind the other. 

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