Definition
In Roman law, a money-lender, money-changer, or banker. The nummularius was a professional figure in the Roman commercial economy who dealt in currency exchange, money-lending, and related financial transactions. The term derives from nummus, the Latin word for coin or money, and describes a person whose occupation centered on the handling and trading of money itself.
The nummularius occupied a recognized role in Roman commercial life, though the precise scope of the term could shade into related figures such as the argentarius, with whom some overlap existed in practice and in legal texts.
Why It Matters in Research
This is a term of purely historical legal significance. Researchers will encounter nummularius almost exclusively in sources dealing with Roman law, Roman antiquities, or the historical development of banking and commercial law. It has no operative meaning in modern common law or civil law systems under this name.
The key navigational point is the relationship between nummularius and argentarius. Burrill's entry directs researchers to argentarius as the companion term, and this cross-reference matters: Roman sources and the legal commentators who drew on them did not always use the two terms consistently. Some authorities treat nummularius as the narrower figure — a coin-tester or money-changer working in retail transactions — while argentarius described the more sophisticated banker engaged in deposits, loans, and account-keeping. Researchers working with Roman commercial law sources should not assume the terms are interchangeable without checking context.
For researchers tracing the intellectual history of banking law or the law of money transmission, nummularius appears in foundational Roman law texts (including the Corpus Juris Civilis, Codex 11.17) and in the antiquarian scholarship that 18th- and 19th-century common law writers drew upon when theorizing about the nature of banking obligations. Burrill's reference to Adam's Roman Antiquities (a standard 19th-century survey) signals that the term circulated in both legal and classical scholarship contexts, meaning it may appear in legal treatises that are not strictly Roman law texts but engage with Roman commercial institutions for comparative or theoretical purposes.
Historical Dictionary Support
Burrill's Law Dictionary provides the sole dictionary treatment in the Law Mind corpus. The entry is brief and accurate to the Roman law sources it cites: the Codex reference (Cod. 11.17.1) and Adam's Roman Antiquities (p. 546) are consistent with the standard 19th-century scholarly treatment of Roman commercial figures.
Burrill correctly flags argentarius as the related term, though the entry does not develop the distinction between the two. The Roman jurists themselves acknowledged gradations: the nummularius was associated with the physical testing and exchange of coins (including the professional duty to verify the quality of coinage), while the argentarius operated more broadly in credit and deposit banking. This distinction, while not fully articulated in Burrill, appears in Adam and in broader Roman law scholarship and is worth attention when the specific capacity of a financial actor matters to a historical legal question.
No other historical dictionary in the Law Mind corpus treats this term. Researchers requiring fuller treatment should consult Roman law commentaries and classical antiquities scholarship directly.
Jurisdictional Note
Nummularius is a Roman law term with no direct equivalent in modern common law or codified civil law systems. Its relevance is historical and comparative. Researchers working in civil law jurisdictions that retain Roman law foundations may find the term in older treatises but will not encounter it in modern statutory or case law.