fossa vs ria

fossa

noun
  • A pit, groove, cavity, or depression. 

  • A large nocturnal reddish-brown catlike mammal (Cryptoprocta ferox) of the civet family, endemic to the rainforests of Madagascar. It is slender, long-tailed and has retractile claws and anal scent glands. 

  • A long, narrow, shallow depression on the body of an extraterrestrial body, such as a planet or moon. 

ria

noun
  • A narrow inlet of the sea formed by a flooded unglaciated river valley. 

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