Definition
Magna centum is a Latin commercial and legal term meaning "the great hundred," equal to 120 units rather than the standard 100. In contexts where magna centum applied, a count of "one hundred" of a particular commodity or item meant six score (6 × 20 = 120), not the arithmetically standard 100. The term was used primarily in mercantile and trading contexts to specify quantities of goods, particularly where trade custom had established the great hundred as the operative unit of measure.
Common Language
Modern common usage (Wiktionary): "Hundred" means the cardinal number equal to ten times ten, or 100.
Historical common usage (Webster's 1913): "Hundred" is defined as ten times ten; a collection or sum of ten times ten units; also used loosely for a great number.
The gap here is historically significant. In medieval and early modern commerce, "hundred" did not uniformly mean 100. Depending on the commodity and the trade custom, a hundred could mean 100 (the centum or small hundred) or 120 (the magna centum, or great hundred). A researcher encountering a contract, inventory, or statute specifying quantities without clarifying which hundred was intended may significantly misread the quantity involved.
Common Confusion
Magna centum is easily confused with the ordinary centum (100). The confusion is compounded because historical documents do not always specify which hundred applies, leaving the operative meaning to be inferred from trade custom, commodity type, or local practice. The great hundred of 120 was standard for certain goods — including fish, nails, and other commodities in English medieval trade — while other goods were counted by the small hundred of 100. Treating all instances of "hundred" as meaning 100 in historical commercial records risks systematic miscounting.
Why It Matters in Research
The primary research risk with magna centum is quantity misreading in historical commercial instruments, statutes, and inventories. When working in the Law Mind corpus with pre-modern mercantile documents, charter records, or commodity regulations, any reference to quantities counted in "hundreds" should be checked against the commodity type and trade custom of the period and jurisdiction. English statutes and trade records through at least the early modern period applied the great hundred (120) to specific goods as a matter of established custom rather than explicit declaration.
The term also surfaces in legal disputes over contract performance and delivery — whether a party who delivered 100 units satisfied a contract calling for a "hundred" depends entirely on which hundred the parties intended. This interpretive question appears in treatise literature and was not purely academic.
Researchers should also be alert to the possibility that secondary sources glossing historical quantities have silently standardized to 100 without noting the great-hundred convention, introducing errors into later scholarship.
Historical Dictionary Support
All four source dictionaries are in complete agreement: magna centum means "the great hundred, or six score." Black's (both editions), Rapalje & Lawrence, and Bouvier all attribute the definition to Wharton, indicating reliance on a common treatise source rather than independent derivation. This uniformity is notable — the definition was treated as settled and uncontroversial across the major nineteenth-century legal dictionaries.
What the historical sources do not do is explain which commodities triggered the great-hundred convention, how disputes over the applicable hundred were resolved, or how the term interacted with statutory weights-and-measures regimes. Researchers needing that level of operational detail must go beyond the dictionary sources to mercantile history and specialized works on historical metrology.
Jurisdictional Note
The great hundred convention was most firmly established in English mercantile practice and carried into early American commerce. Its application varied by commodity and locality. By the nineteenth century, standardization to 100 became increasingly prevalent in statutory and commercial contexts, but residual great-hundred usage persisted in certain trades.