tridem vs triplicate

tridem

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

triplicate

noun
  • Each of a set of three identical objects or copies. 

  • The making of three identical copies of something. 

adj
  • Made thrice as much; threefold; tripled. 

verb
  • To triple. 

  • To make three identical copies of something. 

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