Wiktionary
n. An alternative plan to be put into operation if needed, especially in case of emergencies, or if a primary plan fails
Wikipedia
A contingency plan is a plan devised for an outcome other than in the usual (expected) plan.
It is often used for risk management when an exceptional risk that, though unlikely, would have catastrophic consequences. Contingency plans are often devised by governments or businesses. For example, suppose many employees of a company are traveling together on an aircraft which crashes, killing all aboard. The company could be severely strained or even ruined by such a loss. Accordingly, many companies have procedures to follow in the event of such a disaster. The plan may also include standing policies to mitigate a disaster's potential impact, such as requiring employees to travel separately or limiting the number of employees on any one aircraft.
During times of crisis, contingency plans are often developed to explore and prepare for any eventuality. During the Cold War, many governments made contingency plans to protect themselves and their citizens from nuclear attack. Examples of contingency plans designed to inform citizens of how to survive a nuclear attack are the booklets Survival Under Atomic Attack, Protect and Survive, and Fallout Protection, which were issued by the British and American governments. Today there are still contingency plans in place to deal with terrorist attacks or other catastrophes.
The National Institute of Standards and Technology has published a contingency planning guide for Information Technology Systems (2002).
Usage examples of "contingency plan".
Call General Harris down at the 331st Expeditionary Air Group and tell him the fireworks are about to start in Tikrit and remind him that the contingency plan calls for his F-15s and -16s to fly cover for the exfiltration.
Their existence is still unknown to the humans, but the octospiders have already started formulating a contingency plan to cover a possible interaction with their aggressive neighbors.
It had been devised as a contingency plan, one to be activated only after the Bugs had been decisively weakened, and she recognized his desperate concern for his battered battle-line.
We knew Anu had prepared a contingency plan that was supposed to give him control of the ship no matter what happened, though we had no idea what it was.
All gods bear witness: The Noble House is implementing Contingency Plan One.
Maybe somewhere there had been a contingency plan for this sort of thing, a question Ryan would never bring himself to ask, but whatever the truth was, someone had done well.
The first officials on the scene -- or at least they claimed that distinction -- had been a group of inspectors from the Royal Patent Office, pressed into emergency industrial duty by a Government contingency plan.