substitute vs synthetic

substitute

noun
  • A replacement or stand-in for something that achieves a similar result or purpose. 

  • A player who is available to replace another if the need arises, and who may or may not actually do so. 

  • One who enlists for military service in the place of a conscript. 

verb
  • To remove (a player) from the field of play and bring on another in his place. 

  • To serve as a replacement (for someone or something). 

  • To use in place of something else, with the same function. 

  • To use X in place of Y. 

  • To use Y in place of X; to replace X with Y. 

synthetic

noun
  • A synthetic compound. 

adj
  • Of, or relating to synthesis. 

  • Produced by synthesis instead of being isolated from a natural source (but may be identical to a product so obtained). 

  • Artificial, not genuine. 

  • Produced by synthesis, thought to have the same effect as its natural counterpart, but chemically different from it. 

  • Pertaining to the joining of bound morphemes in a word (compare analytic). 

  • Of a language, having a grammar principally dependent on the use of bound morphemes to indicate syntactic relationships (compare analytic). 

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