hurdle vs retard

hurdle

verb
  • To overcome an obstacle. 

  • To compete in the track and field events of hurdles (e.g. high hurdles). 

  • To jump over something while running. 

  • To hedge, cover, make, or enclose with hurdles. 

noun
  • An artificial barrier, variously constructed, over which athletes or horses jump in a race. 

  • An obstacle, real or perceived, physical or abstract. 

  • A movable frame of wattled twigs, osiers, or withes and stakes, or sometimes of iron, used for enclosing land, for folding sheep and cattle, for gates, etc.; also, in fortification, used as revetments, and for other purposes. 

retard

verb
  • To decelerate; to slow down. 

  • To put off; to postpone. 

  • To keep delaying; to continue to hinder; to prevent from progressing. 

noun
  • Retardation; delay. 

  • A slowing down of the tempo; a ritardando. 

  • A person or being who is extremely stupid or slow to learn. 

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