The difference between Contingency and Inevitability

Contingency as a noun (uncountable):

The quality of being contingent, of happening by chance; unpredictability.

Contingency as a noun (countable):

A possibility; something which may or may not happen. A chance occurrence, especially in finance, unexpected expenses.

Contingency as a noun (countable):

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.

Contingency as a noun (logic, countable):

A statement which is neither a tautology nor a contradiction.

Inevitability as a noun (uncountable):

The condition of being inevitable.

Inevitability as a noun (countable):

An inevitable condition or outcome.