elevated vs metro

elevated

noun
  • An elevated railway. 

adj
  • Of a higher register or style. 

  • Of a higher rank or status. 

  • Raised, particularly above ground level. 

  • Running with administrator rights. 

  • Increased, particularly above a normal level. 

metro

noun
  • A rapid transit rail transport system, or a train in such systems, generally underground and serving a metropolitan area. 

  • An urban rapid transit rail transport system, normally with lighter track and light trains (i.e. an S-Bahn or similar), or a train in such systems. 

  • A metropolitan area. 

adj
  • metropolitan 

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