free fall (
http://definr.com/free fall)
n 1: the ideal falling motion of something subject only to a
gravitational field
2: 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"; "when that became known
the price of their stock went into free fall" [syn:
drop,
fall]