banister vs mullion

banister

noun
  • One of the vertical supports of a handrail; a baluster. 

  • The handrail on the side of a staircase. 

verb
  • To construct a banister 

  • To act as a banister 

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. 

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