A free fall was the movement of an individual or object caused by gravity alone.
In 2267, a turbolift on USS Enterprise carrying James T. Kirk and Spock began descending rapidly, prompting the Vulcan to announce that it was a free fall. (TOS: "Wolf in the Fold")
In 2269, when Sord offered to tackle Tchar, Kirk said he couldn't do it in free fall. (TAS: "The Jihad")
In 2371, Neelix described crew morale on USS Voyager as having been in a free fall, prompting his decision to declare himself morale officer. (VOY: "The Cloud")
In 2372, a turbolift on Deep Space 9 was sent into free fall by someone who used a voice synthesizer to fake Worf's voice, in an assassination attempt on Shakaar Edon. (DS9: "Crossfire")
In 2373, Neelix warned that if a mag-lev carriage's mag-lev cohesion would have to be stabilized, or else the carriage would go into free fall. (VOY: "Rise")