balustrade vs outwork

balustrade

noun
  • A row of balusters topped by a rail, serving as an open parapet, as along the edge of a balcony, terrace, bridge, staircase, or the eaves of a building. 

outwork

verb
  • To work out to a finish; to complete. 

  • To work faster or harder than. 

noun
  • Agricultural work done outdoors in the fields. 

  • A minor, subsidiary fortification built beyond the main limits of fortification. 

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