artery vs metro

artery

noun
  • A major transit corridor in a system of roads, rivers, or railway lines. 

  • Any of the muscular- and elastic-walled blood vessels forming part of the circulation system by which blood is conveyed away from the heart regardless of its oxygenation status; see pulmonary artery. 

  • Hyponyms: alloartery, arteriole, endartery, microartery; see also Thesaurus:artery 

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 artery and metro occurred in a corpus of books? (source: Google Ngram Viewer )