Dictionary.com defines contingent as "dependent on something not yet certain." In the terms of a real estate contract that "something not yet certain" could be the buyers home inspection contingency, financing, or something that you will see in the purchase of a condo - the 3 days the buyer gets to review the condominium documents and financials. If, during the contingency period which is set forth in the contract, the buyer doesn't clear one of the contingencies (ex. is unable to get the financing or property does not pass inspection.), then the contract does not continue. If the contract is "pending" that means that the buyer has gotten through their contingency items and the parties are simply finalizing the paperwork, etc, to close.
I you need any more help with any real estate terms or practices, please don't hesitate to let me know. Karen Peil