blackfish vs porpoise

blackfish

noun
  • A pilot whale, genus Globicephalus (occasionally also used for various other whales). 

  • The Atlantic salmon, Salmo salar, especially a female after spawning. 

  • Any of various dark-coloured fish of the Old World, especially the rudderfish (Centrolophus niger). 

  • Any of various dark-coloured fishes of Australasia, especially the luderick, Girella tricuspidata, and a freshwater fish, Gadopsis marmoratus. 

  • Either of two dark-coloured fish of the west Atlantic, the tautog of New England (Tautoga onitis) and the black sea bass (Centropristis striata). 

verb
  • To go fishing for blackfish. 

  • To adopt signifiers of black identity (for example, by darkening the skin, or wearing traditionally black hairstyles). 

porpoise

noun
  • A small cetacean of the family Phocoenidae, related to dolphins and whales. 

  • Any small dolphin. 

verb
  • Said of an air-breathing aquatic animal such as a porpoise or penguin: To repeatedly jump out of the water to take a breath and dive back in a continuous motion. 

  • Said of an aircraft: to make a series of plunges when taking off or landing; or of a watercraft: to successively plunge up and down in the water. 

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