bilberry vs mountain cranberry

bilberry

noun
  • Vaccinium myrtillus, the wild European blueberry of the cowberry family. 

  • The shrub of the above-mentioned plant. 

mountain cranberry

noun
  • The cowberry, Vaccinium vitis-idaea 

  • The mountain bearberry, Arctostaphylos alpina 

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