Definition
A Roman unit of land measurement, equivalent in English legal usage to an acre. The jugerum was defined by its practical origin: the amount of land a yoke of oxen could plow in a single day. The term appears in early English legal sources, particularly in Coke's commentary on Littleton, where it is used to gloss or explain the English acre in historical context.
Common Language
Modern common usage (Wiktionary): An alternative form of "juger," a Roman unit of area.
Historical common usage (Webster's 1913): Not separately listed; the term was treated as a Latinate technical measure without general currency in English.
The gap here is narrow but worth noting: in ordinary historical usage, "jugerum" was simply a foreign measure. In English legal sources, it appears specifically as a synonym or explanatory parallel for the acre — a legal unit with defined consequences for land tenure, conveyancing, and agrarian obligation. The legal significance lies not in the measure itself but in its use to anchor the English acre to classical authority.
Why It Matters in Research
JUGERUM is a term researchers will encounter primarily in two contexts: early English land law texts (especially those citing or commenting on Coke upon Littleton) and Roman law sources dealing with agrarian measurement.
The navigational trap is treating jugerum as a precise Roman measure equivalent to the English acre without qualification. The Roman jugerum was approximately 28,000 square feet — somewhat smaller than the standard English statute acre of 43,560 square feet. Legal writers citing Co. Litt. used the equivalence loosely, as a learned gloss rather than a precise conversion. Researchers working on disputes involving historical land measurement should not assume the terms are interchangeable without checking the applicable authority and period.
In the Law Mind corpus, jugerum will appear most often in the margins of land law discussions, Roman law treatments, and historical commentaries. It is not a term of operative modern law in any common law jurisdiction; its utility is almost entirely interpretive and historical.
Historical Dictionary Support
Black's Law Dictionary (both editions) and Burrill's Law Dictionary are in complete agreement: jugerum means "an acre," with all three citing Co. Litt. (Coke upon Littleton) as authority and all three providing the same etymological gloss — as much as a yoke (jugum) of oxen could plow in one day. This consistency reflects the term's status as a settled historical reference rather than a contested legal concept.
Burrill adds the related entry JUGULUM (a cut-throat or murderer) and JUGUM (the yoke itself in civil law), which helps situate jugerum within a cluster of Latin agrarian and physical terminology. None of the historical dictionaries address the measurement discrepancy between the Roman jugerum and the English statute acre, which is a meaningful omission for researchers needing precision rather than learned analogy.
The Black's first edition entry contains an anomalous fragment referencing Ferrière and police magistrate functions, which appears to be a printing artifact from an adjacent entry and has no bearing on jugerum. Researchers encountering this in scanned historical sources should disregard it as a digitization or typesetting error.
Jurisdictional Note
Jugerum has no operative legal definition in any modern common law jurisdiction. Its appearance in legal sources is confined to historical texts and classical commentaries. Roman law jurisdictions and civil law systems that draw on Roman agrarian law may treat the jugerum as a defined historical unit, but it does not carry enforceable legal meaning in contemporary practice.