lunge vs retrogression

lunge

verb
  • To (cause to) make a sudden forward movement (present participle: lunging). 

  • To longe or work a horse in a circle around a handler (present participle: lunging or lungeing). 

noun
  • A long rope or flat web line, more commonly referred to as a lunge line, approximately 20–30 feet long, attached to the bridle, lungeing cavesson, or halter of a horse and used to control the animal while lungeing. 

  • A sudden forward movement, especially with a sword. 

  • A fish, the namaycush. 

  • An exercise performed by stepping forward one leg while kneeling with the other leg, then returning to a standing position. 

retrogression

noun
  • A return to a less complex condition. 

  • A deterioration or decline to a previous state. 

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