courgette vs cushaw

courgette

noun
  • A particular variety of Cucurbita pepo, a small marrow/squash. 

  • The edible fruit of this marrow/squash. 

cushaw

noun
  • Any of certain cultivars of Cucurbita argyrosperma (Cucurbita mixta), one of the species of winter squash. 

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