cough drop vs plaquette

cough drop

noun
  • A small, medicated tablet intended to be dissolved slowly in the mouth to relieve coughing symptoms temporarily. 

plaquette

noun
  • A small metal tablet decorated in bas-relief, usually with a design including figures. 

  • The smallest closed loop, enclosing the region between four lattice sites, in lattice gauge theory. 

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