mullion vs skyline

mullion

noun
  • A vertical bar between the panes of glass or casements of a window or the panels of a screen. 

verb
  • To shape into divisions by means of mullions. 

skyline

noun
  • A panel on the front page of a newspaper outlining some of the features to be found inside. 

  • The horizontal silhouette of a city or building against the sky. 

  • The line at which the earth and sky meet. 

  • A path of movement, especially military movement, producing a silhouette above terrain features visible from the location of likely observers. 

verb
  • To filter by means of the skyline operator. 

  • To outline something against the sky. 

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