In civil law systems

Civil law (legal system)

Civil law is a legal system inspired by Roman law and whose primary feature is that laws are codified into collections, as compared to common law systems that gives great precedential weight to common law on the principle that it is unfair to treat similar facts differently on different...

, a synallagmatic contract is a contract

Contract

A contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...

 in which each party to the contract is bound to provide something to the other party. Its name is derived from the Ancient Greek

Ancient Greek

Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 synallagma, meaning mutual agreement. Examples of synallagmatic contracts include contracts of sale, of service, or of hiring.

In common law

Common law

Common law is law developed by judges through decisions of courts and similar tribunals rather than through legislative statutes or executive branch action...

 jurisdictions, it is roughly the equivalent of a bilateral contract rather than a gift

Gift (law)

A gift, in the law of property, is the voluntary transfer of property from one person to another without full valuable consideration...

 (as such a relationship is not one of contract) or a unilateral contract in which only one party makes an enforceable promise. In civilian jurisdictions, the proper contrast is with a gift as such a relationship is one of contract.