Bug vs Serpentine

Bug

name

  • A river in Ukraine (Southern Bug), flowing 530 miles to the Dnieper estuary. 

  • A river flowing northwest 450 miles between Belarus and Poland. 

noun

  • A Bugatti car. 

  • A Volkswagen Beetle car. 

Serpentine

name

  • A river in Alaska. 

  • A river in New Zealand. 

  • A river in Canada. 

  • The lake in Hyde Park, London. 

  • A river in Australia. 

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