Definition
A Latin topographical designation referring to the district or territory of Caermarthen (modern Carmarthen), a town and county in southwest Wales. The term combines the classical Latin *ager* (field, district, territory) with *Maridunensis*, a Latinized adjectival form derived from *Maridunum*, the Roman name for Caermarthen. In legal and administrative contexts, it denotes the lands, jurisdiction, or territorial extent associated with Caermarthenshire as understood in Latin documentary sources.
Why It Matters in Research
This term appears almost exclusively in medieval and early modern Latin legal instruments — charters, grants, ecclesiastical records, and administrative documents — where Welsh place-names were rendered in Latinized form. Researchers encountering *Ager Maridunensis* in primary sources should understand that it designates Caermarthenshire or the Caermarthen district specifically, not some abstract geographic region. Failure to recognize the Latinized Roman place-name *Maridunum* as Caermarthen can cause significant mislocation of the territory under discussion.
The term is a navigational challenge because Welsh place-names were Latinized inconsistently across the medieval period, and variant spellings of *Maridunensis* occur in the corpus. Researchers should cross-check against related topographical Latin terms when working with Welsh estate records, monastic cartularies, or crown grants involving southwest Wales.
Note also that Burrill's entry for this term appears within a list of similar topographical Latinisms — including entries for Lancashire, Whitby Castle in Cumberland, Warwickshire's River Alne, and a Denbighshire reference — suggesting that *Ager Maridunensis* was one of several such region-identifiers catalogued for the practical use of lawyers and clerks decoding Latin documents. This context signals that the term had active documentary use sufficient to warrant inclusion in a practitioner reference.
Historical Dictionary Support
Burrill's Law Dictionary provides only a bare identification: the entry links *Ager Maridunensis* to Caermarthenshire, presented alongside other Welsh and English topographical Latinisms without elaboration. The entry is purely referential — it offers no discussion of the term's use in specific legal instruments, its jurisdictional significance, or its historical frequency in the record. No other standard historical legal dictionaries in the Law Mind corpus appear to address this term independently.
The sparseness of Burrill's treatment is itself informative: such topographical entries were included as decoding aids for practitioners confronted with Latin documents, not as substantive legal concepts. The term carries no doctrinal content of its own; its legal significance is entirely derivative of whatever instrument or proceeding invoked it.
Jurisdictional Note
Relevant exclusively to legal and documentary history concerning Wales, particularly southwest Wales. Modern legal proceedings have no use for this term; its relevance is confined to historical research involving Welsh land records, crown administration, and ecclesiastical documents produced during periods when Latin was the documentary language of record.