Comment on the definition of contract
The definition of a contract according to the reader is partially correct. It conveys messages that if an agreement is free from any kind of factors which would in turn make the contract ineffective, like mistake or misinterpretation then it would not be void. So we say that contract is a enforceable agreement between two parties or may be more. Once the contract is signed between the two parties the contract involves a reasonably precise set of terms and conditions, and both the parties are obliged to enforce these terms and conditions in order to get the contract going or sanctioned.
As the parties have signed a particular contract now the contract is not free from the taint of illegality and immorality. Also not subsequently discharged by law, breach or by supervening circumstances. If amongst the two parties one of the party do not understand the contract or partially understand it then the contract would be void as there is an imbalance of understanding between the two parties. Also if the contract is illegal then the contract will be void. The contract can be void even in the situation when a person is drunk as the person lacks the ability to consent or in case of minors, the contract will be void as there was no consent from the other party.
So the reader understands that if a particular contract is signed it is not necessary that it will not be void, it depends on various different situations where it can still be void. For a contract not be void it has to be totally moral, legal and understood by all the parties involved.