Definition
A Latin place-name designation for Kingston-upon-Thames, a historic town in Surrey, England. The term is a Latinized rendering used in legal and formal documents, particularly those produced during periods when Latin was the standard language of English legal records. "Regiodunum" renders the element "king's town" (from Old English *Cyningestun*), and "Thamesinum" anchors the place to the River Thames, distinguishing it from other similarly named settlements.
Why It Matters in Research
Researchers encountering this term will most likely find it in pre-nineteenth-century legal instruments — royal charters, writs, borough records, ecclesiastical documents, or pleadings recorded in Latin before the use of Latin in English legal proceedings was abolished by statute in the eighteenth century. The term has no operative legal meaning of its own; it functions purely as a place identifier. Its significance in research is navigational: a document referencing "Regiodunum Thamesinum" is a document concerning Kingston-upon-Thames, its courts, its borough franchise, or property within its jurisdiction.
The primary trap for researchers is failure to recognize the term at all, particularly when searching across digitized historical corpora using keyword or string-matching tools. Because the Latinized form bears no obvious resemblance to the modern English name, full-text searches for "Kingston" or "Kingston-upon-Thames" will not surface documents that use this designation. Conversely, searching for "Regiodunum" without awareness of the Surrey location may produce confusion with similarly constructed Latin place-names elsewhere.
A secondary consideration: Surrey's historical jurisdictional complexity, including the peculiar status of Kingston as a royal borough with its own chartered privileges, means that documents using this Latin form may implicate borough court records, quarter sessions, or Crown grant instruments that sit in distinct archival silos from ordinary county records.
Historical Dictionary Support
Burrill's Law Dictionary provides the entry in its most compressed possible form: "Kingston-upon-Thames in Surrey." This is the entirety of Burrill's treatment, which is consistent with how legal dictionaries of the nineteenth century handled Latin topographical terms — they functioned as glossaries to unlock place-names encountered in older instruments rather than as substantive doctrinal entries. No legal rule or principle attaches to the term itself.
No other historical legal dictionaries in the Law Mind corpus appear to carry this entry. Burrill, with his extensive attention to Law Latin and technical vocabulary drawn from English legal records, is the natural home for this kind of geographical gloss. Researchers should not expect doctrinal analysis from any source on this term; its dictionary life is purely definitional in the geographic sense.
Jurisdictional Note
This term is exclusively English in origin and application. It appears in instruments connected to the English common law tradition and has no application in American, Scottish, or other common law jurisdictions. For English legal history research, the relevant jurisdiction is Surrey, with Kingston-upon-Thames carrying the additional status of a royal borough throughout much of the medieval and early modern period.