duad vs spark

duad

noun
  • A pair or couple. 

  • Dwadasama. 

  • An unordered pair. 

spark

noun
  • A beau, lover. 

  • A small, shining body, or transient light; a sparkle. 

  • Any of various lycaenid butterflies of the Indomalayan genus Sinthusa. 

  • An electrician. 

  • A small amount of something, such as an idea or romantic affection, that has the potential to become something greater, just as a spark can start a fire. 

  • A small particle of glowing matter, either molten or on fire. 

  • A ship's radio operator. 

  • A short or small burst of electrical discharge. 

  • A gallant; a foppish young man. 

verb
  • To shoot; to fire 

  • To trigger, kindle into activity (an argument, etc). 

  • To give off a spark or sparks. 

  • To light; to kindle. 

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