limetta vs sweet lemon

limetta

noun
  • Citrus limetta, a small, round, sweet citrus fruit, a cross between the citron and bitter orange. 

sweet lemon

noun
  • A plant of the species Citrus medica (syn. Citrus limetta) or its fruit. 

  • Any of several plants that produce fruit resembling lemon or lime, but less acidic than lemon. 

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