buttercup vs sugar-plum

buttercup

noun
  • Affectionate or ironic term of address. 

  • Any of many herbs, of the genus Ranunculus, having yellow flowers; the crowfoot. 

  • Any flower of the genus Narcissus; a daffodil. 

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 buttercup and sugar-plum occurred in a corpus of books? (source: Google Ngram Viewer )