sweetheart vs waterleaf

sweetheart

noun
  • A person who is always very kind. 

  • A person very much liked or loved by someone, especially when both partners are young. 

  • A female member of a college or university fraternity. 

waterleaf

noun
  • Any plant of the genus Hydrophyllum. 

  • A tropical plant (Talinum fruticosum), the leaves of which are eaten as a vegetable. 

  • A leaf-shaped decoration used on the capitals of columns in late 12th-century Romanesque architecture 

  • An absorbent unsized paper like blotters as opposed to slake-sized or hard sized papers. 

  • Any plant of Hydrophyllaceae, the waterleaf family. 

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