Whats is the Definition of Agreement

It depends on the contents written on it (whether agreeement or not).  But from the facts above it can be termed as proof of transaction and any dispute can be referred to court.

As per Contract Act, an agreement enforceable by law is a contract. [section 2(h)]. Hence, we have to understand first what is ‘agreement’.

Every promise and every set of promises, forming the consideration for each other, is an agreement. [section 2(e)]. - - A person makes a proposal (offer). When it is accepted by other, it becomes a promise. However, promise cannot be one sided. Only a mutual promise forming consideration for each other is ‘agreement’. - - For example, A agrees to pay Rs 100 to B and B agrees to give him a book which is priced at Rs 100. This is set of promises which form consideration for each other. However, if A agrees to pay Rs 100 to B, but B does not promise anything, it is not ‘set of promises forming consideration for each other’ and hence not an agreement.