hindrance vs retardant

hindrance

noun
  • Something which hinders: something that holds back or causes problems with something else. 

  • The state or act of hindering something 

retardant

noun
  • Something that serves to retard (slow down) the action of something 

adj
  • Serving to impede (slow down) the action of something 

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