staircase vs stairway

staircase

noun
  • A connected set of flights of stairs; a stairwell. 

  • A flight of stairs; a stairway. 

  • A set of locks (enclosed sections of waterway) mounted one above the next. 

verb
  • To modify (a signal, a graph, etc.) to reduce a smooth curve to a series of discrete steps. 

  • To increase one's share in a co-ownership. 

stairway

noun
  • A set of steps, with or without a case, that allow one to walk up or down. 

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