balustrade vs peanut gallery

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. 

peanut gallery

noun
  • In the nineteenth century, the cheap seats at the back of a theatre or in the upper balcony. 

  • Any source of heckling, unwelcome commentary or criticism, especially from a know-it-all or of an inexpert nature. May also now refer to general audience response: "Let's hear it from the peanut gallery." 

  • The upper balcony to which black patrons were restricted in racially segregated venues such as theatres. 

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