Definition
In Roman law, a subdivision of the as equal to two unciae, representing the proportion of two-twelfths, or one-sixth, of the whole. The as was the foundational unit of Roman reckoning used across both monetary and inheritance contexts, and the sextans expressed a fractional share of that unit. When appearing in legal texts — particularly in relation to succession — the sextans designates a one-sixth portion of an estate assigned to an heir or legatee.
Common Language
Modern common usage (Wiktionary): A Roman coin worth one sixth of an as.
Historical common usage (Webster's 1913): A Roman coin, the sixth part of an as; also, a constellation on the equator south of Leo.
The gap between common and legal meaning is narrow but worth noting. Common usage treats the sextans primarily as a coin — a physical object of monetary value. In Roman legal sources, the term functions primarily as a fractional unit of account, not necessarily a physical coin. In inheritance law, "ex sextante heres institutus" means an heir instituted to receive a one-sixth share of the estate, a purely proportional concept that has nothing to do with a coin passing hands. Researchers reading Roman succession documents should approach sextans as an arithmetic fraction first, a currency denomination second.
Why It Matters in Research
Sextans is a narrow term of Roman law with no surviving equivalent in modern common law or civil law systems. It appears in Law Mind corpus materials almost exclusively in two contexts: (1) explanatory footnotes and glossaries in commentaries on Roman inheritance law, and (2) comparative law treatments of the as and its fractional subdivisions.
The principal research trap is treating the term as solely monetary when it frequently performs a purely fractional function in succession instruments. Roman testators used the twelve-part division of the as as a standard framework for apportioning estates among multiple heirs. A sextans share meant two of twelve parts — a mathematical allocation, not a reference to coin. Researchers working with translated Roman legal texts should verify whether a given translator has rendered sextans as "one-sixth" (correct for legal context) or as "a coin" (potentially misleading).
The term also connects to a broader vocabulary of Roman fractional units — uncia, triens, quadrans, semis, and others — that appear throughout classical civil law sources and their English commentaries. Blackstone's footnote treatment (2 Bl. Comm. 462, note) situates sextans within this system for English-trained readers, and Burrill's citation to Taylor's Elements of the Civil Law provides a secondary explanatory source within the historical dictionary shelf.
Because sextans has no living legal application, researchers encounter it almost exclusively when tracing the historical background of fractional inheritance rules or when working with primary Roman legal texts such as the Digest or the Theodosian Code, where the term appears in succession and property contexts.
Historical Dictionary Support
The three shelf sources — both editions of Black's and Burrill's — are in complete agreement: sextans is a subdivision of the as containing two unciae, equal to one-sixth. The definitions are nearly identical across all three, with Burrill adding a citation to Taylor's Civil Law and the Blackstone footnote that Black's (1st ed.) also carries. Black's 2nd edition truncates slightly, omitting the proportional gloss, but adds nothing divergent.
None of the legal dictionary sources address the succession-instrument usage directly, focusing instead on the monetary-unit framing. The Latin dictionary tradition (Varro, the Digest, the Theodosian Code) is richer on the legal application: "heredes in sextante" and "ex sextante heres institutus" from classical sources show the term operating as an inheritance fraction, a dimension the legal dictionaries gesture toward without fully developing.
What the historical dictionaries miss: no shelf source explains the twelve-part as system in enough detail to allow a researcher unfamiliar with Roman law to place sextans within its proper framework. A researcher encountering the term in a primary source needs to look beyond any of these dictionary entries to a civil law treatise or commentary for full context.