ophidian vs serpent

ophidian

noun
  • Any species of the suborder Serpentes; a snake or serpent. 

adj
  • Of or pertaining to the suborder Serpentes; of, related to, or characteristic of a snake or serpent. 

serpent

noun
  • A snake, especially a large or dangerous one. 

  • An obsolete wind instrument in the brass family, whose shape is suggestive of a snake (Wikipedia article). 

  • A kind of firework with a serpentine motion. 

  • A subtle, treacherous, malicious person. 

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