free fall

noun
  1. 1

    The state of being in a motion affected by no acceleration (force) other than that provided by gravity.

  2. 2

    (common usage) The state of falling with no interference from outside forces other than the air resistance (no open parachute, etc.)

  3. 3

    (by extension) The state of worsening out of control.

    โ€œAs civil war continues in Iraq, the U.S. president's approval ratings are in freefall.โ€

Source: https://en.wiktionary.org/wiki/free%20fall, https://en.wiktionary.org/wiki/freefall