mediate vs stand in

mediate

verb
  • To resolve differences, or to bring about a settlement, between conflicting parties. 

  • To divide into two equal parts. 

  • To act as an intermediary causal or communicative agent; to convey. 

  • To intervene between conflicting parties in order to resolve differences or bring about a settlement. 

  • To act as a spiritualistic medium. 

adj
  • Gained or effected by a medium or condition. 

  • Acting through a mediating agency, indirect. 

  • Intermediate between extremes. 

stand in

verb
  • To take a side in a dispute. 

  • To substitute for; to replace; (theater) to serve as an understudy. 

  • To make one of a party in a bet or other speculation. 

noun
  • A substitute; a replacement. 

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