downward vs dropping

downward

adj
  • Located at a lower level. 

  • Moving, sloping or oriented downward. 

adv
  • At a lower level. 

  • Southward. 

  • Toward a lower level, whether in physical space, in a hierarchy, or in amount or value. 

dropping

noun
  • The act of something that drops or falls. 

  • Something dropped; a droplet. 

  • A piece of animal excrement; dung. 

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