heartling vs sugar-plum

heartling

noun
  • A term of endearment, similar to darling. 

sugar-plum

noun
  • Term of endearment: sweetheart, darling. 

  • A round or oval sweet/piece of candy made of boiled sugar. 

How often have the words heartling and sugar-plum occurred in a corpus of books? (source: Google Ngram Viewer )