free fall in WordNet English dictionary

1. a sudden sharp decrease in some quantity
   "a drop of 57 points on the Dow Jones index"; "there was a drop in pressure in the pulmonary artery"; "a dip in prices"; "when that became known the price of their stock went into free fall"
   drop  dip  fall  free fall 
   
2. the ideal falling motion of something subject only to a gravitational field
   free fall 
   

free fall in English Wiktionary