Steve:
"Fraud in the inducement is an equitable defense, and occurs when A signs a contract, knowing that it is a contract and (at least having a rough idea) what the contract is about, but the reason A signed the contract was because of some false information that B gave to A. For example, if John tells his mother to sign a deed giving him her property, Mom refuses at first, then John explains that the deed will be kept in a safe deposit box until she dies. If Mom signs the deed because of this statement from John, and John tries to enforce the deed prior to Mom's death, Mom can plead "fraud in the inducement."
From Wikipedia.