crosswalk vs underpass

crosswalk

noun

  • A point designated for pedestrians to cross a street. 

  • A mapping between equivalent elements (fields) in different database schemas. 

verb

  • To map equivalent elements (fields) in different database schemas. 

underpass

noun

  • A passage that crosses a road, railroad or similar obstacle in a tunnel underneath it. 

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