bittersweet vs heliotrope

bittersweet

noun
  • A vine, of the genus Celastrus, having small orange fruit that open to reveal red seeds. 

  • A pinkish-orange color. Any color in between scarlet and orange. 

  • Bittersweetness. 

  • Bittersweet nightshade, Solanum dulcamara. 

  • Any variety of clam in the family Glycymerididae 

  • A variety of apple with a bittersweet taste. 

adj
  • Both bitter and sweet. 

  • Expressing contrasting emotions of pain and pleasure. 

  • Of bittersweet color. 

heliotrope

noun
  • A plant that turns so that it faces the sun. 

  • A light purple or violet colour. 

  • Particularly, a purple-flowered plant of the species Heliotropium arborescens. 

  • A bloodstone (a variety of quartz). 

  • An instrument, employed in triangulation, that uses a mirror to reflect sunlight toward another, very distant, surveyor. 

  • The fragrance of heliotrope flowers. 

adj
  • Light purple or violet. 

  • Keeping one’s face turned toward the sun. 

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