Definition
In old English and Anglo-Norman legal usage, *serment* is the Law French term for an oath — a solemn affirmation or sworn declaration carrying legal force. The term appears in medieval English legal records and year books where proceedings were conducted in Law French, the professional language of the common law courts from roughly the Norman Conquest through the late seventeenth century. It is the direct functional equivalent of the Latin *sacramentum* and the English "oath," and carried the same legal weight as either in the records where it appears.
The term is not a term of art with distinct legal elements of its own; it is a linguistic label for the concept of the oath, transposed into Law French. Its significance to legal research is primarily philological and historical rather than doctrinal.
Common Language
Modern common usage (Wiktionary): *Serment* is a standard French word meaning "oath" or "vow," used in contemporary French in both formal and ordinary contexts (e.g., *prêter serment*, to take an oath).
Historical common usage (Webster's 1913): Not entered. The term had fallen from English common use well before the nineteenth century and would have been recognizable only to readers of old French or legal history.
Editorial note: Unlike many Law French survivals that evolved into terms of art, *serment* never detached from its ordinary meaning. The legal and common meanings are identical in content; the research gap is purely one of context — the word appears in English legal records not as French but as the operative legal vocabulary of the medieval common law.
Why It Matters in Research
Researchers encountering *serment* in year book entries, plea rolls, or early English statutes should recognize it immediately as "oath" and not treat it as a specialized legal concept requiring separate analysis. The danger is the opposite of most Law French terms: because the word is transparent to anyone with French, there is a temptation to read it through a modern French lens without appreciating that its legal significance is governed entirely by the English common law doctrine of oaths operative at the time of the record.
The year book citation preserved in Burrill — *le loy est lie par son serment à faire ses liges droit* ("the king is bound by his oath to do his lieges justice," Year Book, Hilary Term, 8 Henry VI, f. 6) — illustrates a significant doctrinal deployment: the royal coronation oath as a source of legal obligation running from the Crown to its subjects. Researchers working on prerogative, constitutional history, or the origins of judicial review will find this framing relevant; the oath here is not merely ceremonial but is invoked as a legal constraint on sovereign conduct.
In corpus searching, *serment* will surface almost exclusively in pre-1650 materials. After the formal abolition of Law French in court proceedings (by statute in 1650, revived and finally ended by 1731), the term disappears from English legal writing except in historical commentary and glossaries. Searching for oath-related doctrine in records spanning this period requires cross-referencing *serment*, *sacramentum*, and "oath" to capture the full record.
Historical Dictionary Support
The three source dictionaries agree completely on the core definition: *serment* means "oath" in old English law and derives from the Latin *sacramentum*. There is no divergence among them on meaning.
Burrill adds the most research value by providing the year book quotation demonstrating the term in substantive use, and by explicitly tracing the derivation from *sacramentum* — a cross-reference that connects *serment* to the far richer Latin apparatus of oath doctrine developed in canon and civil law. Black's (1st ed.) appends several Latin maxims on speech and interpretation (*sermo index animi*; *sermones semper accipiendi sunt secundum subjectam materiam*) in the same textual neighborhood, though these maxims relate to the Latin *sermo* (speech, word) rather than to *serment* directly — a layout artifact of the dictionary's alphabetical structure that could mislead a researcher into treating these maxims as glosses on *serment* itself. They are not. Black's (2nd ed.) is the most spare, offering only the gloss "oath" with a cross-reference.
No historical dictionary provides substantive treatment of the doctrine of oaths itself under this heading; all treat *serment* as a vocabulary entry pointing elsewhere.
Jurisdictional Note
As a Law French term, *serment* is specific to the English common law tradition and its derivative jurisdictions. It does not appear as operative legal vocabulary in Scots law, which drew on a separate Latin and Scots vernacular tradition, nor in continental European legal systems, where the French word retained its ordinary meaning without acquiring the specialized valence of a legal term of art.