English law has no formal definition of the contract. In the absence of a Code it has not needed one, moreover any such definition is not a part of the law itself. Very generally it can be said that by the contract is usually understood a commercial agreement which gives rise to obligations enforced and recognised by law.
L'Estrange v Graucob  2 KB 394 per Scrutton LJ:
When a document containing contractual terms is signed, then, in the absence of fraud, or, I will add, misrepresentation, the party signing it is bound, and it is wholly immaterial whether he has read the document or not.
…In this case the plaintiff has signed a document headed ‘Sales Agreement’, which she admits had to do with an intended purchase, and which contained a clause excluding all conditions and warranties. That being so, the plaintiff, having put her signature to the document and not having been induced to do so by any fraud or misrepresentation, cannot be heard to say that she is not bound by the terms of the document because she has not read them.
In CH Rugg & Co Ltd v Street  1 Lloyd’s Rep 364, at page 369 McNair J said:
The next point is: is it clear that the negotiations created a binding contract, or were the negotiations all contingent upon the signature by both parties of a formal agreement. That matter has been considered by me and in the Court of Appeal in two cases which I have been referred to, the first being Sociedade Portuguesa de Navios Tanques Limitada v Hvalfangerselskapet Polaris A/S  1 Lloyd’s Rep 71 and in the Court of Appeal in the same volume at page 407, on which I had occasion to refer to the authorities which I need not now repeat; and again in a rather similar case Zarati Steamship Co Ltd v Frames Tours Ltd  2 Lloyd’s Rep 278, and without repeating what I have said there, it really amounts to this. That in each case the court has got to make up its mind on the construction of the documents and on the general surrounding circumstances whether the negotiations were not to have contractual force until a formal document was signed.