cetacean vs sperm whale

cetacean

noun
  • An animal belonging to the order Cetacea, including dolphins, porpoises, and whales. 

adj
  • Resembling or relating to large aquatic mammals. 

  • Pertaining to the zoologic order Cetacea, or associated with species falling under that taxonomic hierarchy. 

sperm whale

noun
  • A whale (Physeter catodon, syn. Physeter macrocephalus), the largest of the toothed whales. 

  • Any whale in the superfamily Physeteroidea, which also includes the small whales of genus Kogia. 

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