combinative vs synergistic

combinative

adj
  • Serving, tending, or able to combine. 

  • Of, pertaining to, or resulting from combination. 

synergistic

adj
  • Of or pertaining to synergy or synergism; synergic; co-operative, working together, interacting, mutually stimulating. 

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