Definition
In civil law, to lend a thing to another person for use, with the expectation that the same thing will be returned. Commodare describes the act of lending — the operative verb underlying the contract of commodatum. The lender (commodans) transfers possession but not ownership of a specific thing to the borrower (commodatarius), who uses it gratuitously and returns the identical object when use is complete.
Commodare is closely tied to commodatum, the contract that the act creates. The term appears in classical Roman law sources and in legal systems derived from the civil law tradition, where it functions as the root verb from which the full doctrinal apparatus of gratuitous lending is built.
Common Confusion
COMMODARE, COMMODATUM, and MUTUUM are related but distinct. Commodare is the act of lending for use; commodatum is the contract that results from that act. Mutuum, by contrast, is a loan of consumable things (money, grain) where the borrower returns equivalent things of the same kind and quantity, not the identical object. The distinction matters because commodatum transfers possession only, while mutuum transfers ownership — carrying different consequences for risk, liability, and the nature of the borrower's obligation. Researchers encountering any of these terms in civil law sources should confirm which relationship is being described before drawing doctrinal conclusions.
Why It Matters in Research
Researchers working in civil law sources, Louisiana materials, Quebec law, Scots law, or any jurisdiction drawing on the Roman tradition will encounter commodare and its cognates frequently. The term rarely appears in common law sources by name, but the underlying concept — gratuitous lending for use — is addressed in common law under the language of bailment, specifically a bailment for the sole benefit of the bailee.
The key research trap is treating commodare and commodatum as interchangeable. Burrill and other nineteenth-century dictionaries often define one by reference to the other without drawing the verb/noun distinction clearly. When reading historical sources, determine whether the author is describing the act, the contract, or the resulting obligation.
A second trap concerns the gratuitous element. Commodare in classical civil law is strictly gratuitous — no compensation flows to the lender. If compensation is involved, the transaction shifts toward hire (locatio conductio). Some secondary sources blur this line when describing early American commercial arrangements; verify gratuitousness before applying civil law doctrine.
For corpus researchers, commodare is most productive as a gateway term. Tracing it through civil law digests will lead to the fuller commodatum entries, which carry the substantive rules on liability, care, and risk. The Institutes and the Digest are the foundational primary sources; Burrill points specifically to Inst. 3.14 and Dig. 13.6.
Historical Dictionary Support
Burrill defines commodare plainly as "to loan or lend; to give a thing to another to be used," citing Justinian's Institutes (Book 3, Title 14) and the Digest. This is accurate and consistent with classical Roman law doctrine. The definition is economical to the point of being skeletal — it identifies the act but does not address the essential features that distinguish commodare from other forms of lending: the gratuitous character, the requirement that the identical thing be returned, and the lender's retention of ownership.
Historical dictionaries generally treat commodare as a simple entry because the doctrinal weight is carried by commodatum. Researchers relying on Burrill alone will need to supplement with the commodatum entry and with civil law treatises to obtain the full picture. The Institutes passage cited (3.14) is the classical source for the proposition that a loan for use differs from a loan for consumption precisely because the borrower in commodatum is bound to return the same thing.
No significant disagreement exists among historical sources on the core meaning of commodare. The variation lies in how thoroughly individual dictionaries develop the surrounding doctrine.
Jurisdictional Note
Commodare and commodatum remain operative doctrinal terms in Louisiana, Quebec, and other mixed or civil law jurisdictions. In common law jurisdictions, the concept survives under bailment doctrine without Roman nomenclature. Researchers crossing between civil and common law sources on gratuitous lending must translate terminology carefully, as the analytical frameworks differ even when the underlying fact patterns are identical.