The quantity of payment in return for some amount of goods or services. In modern economies, the quantity of payment is in the form of currency.
Price is considered an equilibrium point where the buyer and seller agree on the quantity to exchange. In a free market, both parties have the option of accepting the terms or walking away.
Under monopolistic conditions, this is negated since price is set without little choice of alternative action. This usually involved government oversight as in the case of utilities.