free fall

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The fall of a body within the atmosphere without a drag-producing device such as a parachute.
• noun The ideal falling motion of a body that is subject only to the earth's gravitational field.
• noun Rapid uncontrolled decline.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A variant form of freefall.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the ideal falling motion of something subject only to a gravitational field
• noun a sudden sharp decrease in some quantity