correlative vs synergic

correlative

adj
  • Mutually related; corresponding. 

noun
  • A pro-form; a non-personal pronominal, proadjectival, or proadverbial form 

  • Either of two correlative things. 

synergic

adj
  • Of or pertaining to synergy; synergistic 

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