What is Consensual?

Legal Definition
Civil law. This word is applied to designate one species of contract known in the civil laws; these contracts derive their name from the consent of the parties which is required in their formation, as they cannot exist without such consent.

2. The contract of sale, among the civilians, is an example of a consensual contract, because the moment there is an agreement between the seller and the buyer as to the thing and the price, the vendor and the purchaser have reciprocal actions On the contrary, on a loan, there is no action by the lender or borrower, although there may have been consent, until the thing is delivered or the money counted. This is a real contract in the sense of the civil law. Lec. El. Dr: Rom. 895; Poth. Ob. pt. 1, c. 1, s. 1, art. 2; 1 Bell's Com. (5th ed.) 435. Vide Contract.
-- Bouviers Law Dictionary
Legal Definition
A contract that can be oral or written and is agreed to by the parties involved.
Legal Definition
Depending upon consent.
-- Ballentine's Law Dictionary