Definition
Latin. A sign, mark, or seal. Signum appears in legal sources across three distinct contexts:
1. Roman and civil law — A sign, mark, or the seal affixed to an instrument. In this sense, signum functions as authentication: the physical mark that vouches for the genuineness of a document or legal act.
2. Roman law of proof — A category of evidentiary indication. Signa, in the plural, denoted those species of indicia that come directly under the cognizance of the senses, as distinguished from more inferential forms of proof. Physical traces perceptible to direct observation — blood stains on a suspect's person, for example — were classified as signa rather than as presumptions or circumstantial inferences of a more abstract character.
3. Saxon law — The sign of the cross prefixed to a charter or deed as an expression of assent and approval. Before universal literacy and standardized sealing practices, the cross served as the subscribing mark of parties who could not write. This use of signum bridges the gap between Roman sealing practice and medieval Anglo-Saxon documentary form.
Common Language
Modern common usage (Wiktionary): A sign, mark, or symbol; a medieval tower bell used to ring the canonical hours; in mathematics, a function extracting the sign of a real number.
Historical common usage (Webster's 1913): Not separately defined as an English word; treated as a Latin term.
The mathematical and campanological senses of signum are wholly irrelevant to legal sources. The critical gap is narrower: ordinary usage treats signum as any generic mark or symbol, while legal sources use it as a technical term for a specific evidentiary category (sensory indicia) and for the authenticating seal or cross on a document — roles with defined legal consequences that a mere "mark" does not carry.
Common Confusion
Signum is sometimes read interchangeably with sigillum (a small seal or signet) and with subscriptio (a written subscription). They are related but distinct: sigillum specifically denotes the wax or impressed seal device; subscriptio denotes a written signature or subscription; signum is the broader term encompassing any authenticating mark, including the cross of Saxon practice. In evidentiary contexts, signum must also be distinguished from indicium (a circumstantial inference or trace leading to an inference), though classical and civil-law writers use the terms in overlapping ways.
Why It Matters in Research
Researchers will encounter signum in three clusters of Law Mind sources that require different reading strategies.
First, in Roman law and civil-law texts, signum as seal or authenticating mark is central to questions of documentary validity. Sources discussing the sealing of wills, the authentication of charters, and the execution requirements for formal instruments will use signum in this sense. Pay attention to whether a source distinguishes signum from sigillum — some civilian writers treat them as synonymous; others maintain a strict distinction.
Second, in civil-law and early common-law evidence treatises, signa as a category of proof represents an early attempt to taxonomize evidence. The classification of sensory indicia as signa — distinct from more inferential presumptions — matters for understanding how pre-modern courts thought about the relationship between physical evidence and proof. Researchers working in legal history of evidence will find this usage in treatises such as Best on Presumptions (cited by all three source dictionaries) and in Fleta (cited by Burrill). These are genuine historical sources; the Digest citation in Burrill (Dig. 28.1.22.3, 5) relates to wills and sealing, not to the evidentiary category, so care is needed when following citations.
Third, in diplomatic and charter history, signum as the Saxon cross is essential context for medieval document study. Anglo-Saxon charters frequently record the signa of witnesses and grantors as crosses, sometimes labeled with the individual's name added by a scribe. Researchers consulting charter collections or works on medieval conveyancing will need to recognize that signum in this context signals subscription by mark, not by formal seal.
Jurisdictional and temporal traps: Signum has no operative meaning in modern common-law pleading or statutory drafting; it appears almost exclusively in historical, civil-law, or ecclesiastical sources. Researchers who encounter it in a modern document are almost certainly reading a quotation, a historical reference, or a civil-law authority.
Historical Dictionary Support
Black's (both editions) and Burrill agree closely on the three-sense structure — seal, evidentiary indicator, and Saxon cross — which reflects a stable civilian and historical tradition. Burrill adds the Digest reference and explicitly cites Fleta, giving the entry stronger primary-source grounding. Best on Presumptions is cited by all three for the evidentiary category.
None of the three sources develops the evidentiary sense at length, and none explains the theoretical framework — drawn from classical rhetoric and civilian procedure — within which signa were distinguished from other proof categories such as praesumptiones and argumenta. Researchers needing that framework will need to go beyond the dictionary entries to civilian evidence treatises directly.
The Latin dictionary tradition (Lewis & Short) confirms the breadth of the classical term — mark, token, sign, military standard, constellation, seal — of which legal usage selects and narrows several specific applications. That narrowing is itself jurisprudentially significant and the dictionaries do not explain it.
Jurisdictional Note
Signum as a legal term of art is confined to Roman law, civil-law systems, ecclesiastical law, and historical English sources predating the systematic development of common-law sealing and signature practice. It carries no operative force in modern common-law jurisdictions and is not defined in contemporary statutory codes.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Seals and Sealing (documentary authentication); Evidence — Historical Classifications of Proof; Anglo-Saxon Charter Practice.