demilune vs sickle-shape

demilune

noun
  • A fortification constructed beyond the main ditch of a fortress, and in front of the curtain between two bastions, intended to defend the curtain; a ravelin. 

  • A crescentic mass of granular protoplasm present in the salivary glands. 

adj
  • In the shape of a half-moon, i.e. semicircular. 

sickle-shape

How often have the words demilune and sickle-shape occurred in a corpus of books? (source: Google Ngram Viewer )