Contingency

noun

1. The quality of being contingent, of happening by chance; unpredictability.
2. A possibility; something which may or may not happen. A chance occurrence, especially in finance, unexpected expenses.
3. An amount of money which a party to a contract has to pay to the other party (usually the supplier of a major project to the client) if he or she does not fulfill the contract according to the specification.
4. A statement which is neither a tautology nor a contradiction.