cassette vs cough drop

cassette

noun
  • Any similar small cartridge, such as for a computer disk or cassette air conditioner 

  • A small flat case containing magnetic tape on two reels, used to record and play back audio and video material. 

  • A saggar (ceramic container used in a kiln) 

  • A modular DNA sequence encoding one or more genes for a single biochemical function. 

  • A lightproof container for photographic film. 

  • A set of sprockets mounted onto a splined shaft on the freehub. 

cough drop

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

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