free fall
1. A vertical descent of a physical body in which gravity is the only force acting upon it. If they were in true free fall, a feather and a bowling ball would both fall to the ground at the same rate.
2. In a parachute jump, the period of vertical descent leading up to and immediately before the parachute is opened. I get such a rush from the free fall when I skydive that I often wish I didn't have to open my chute at all!
3. By extension of def. 1, any sudden, rapid, and uncontrollable decline (e.g., in value, reputation, success, etc.) that continues unabated for an indefinite length of time. The stock market went into a free fall after the housing market collapsed. After getting busted by the police for using marijuana last year, John's life has been in a free fall.
free fall
A rapid, uncontrolled decline, as in The markets threatened to go into free fall and we came close to outright panic. This term transfers the aeronautical meaning of a free fall, that is, "a fall through the air without any impedance, such as a parachute," to other kinds of precipitous drop. [Second half of 1900s]